It was an attack that echoed the carnage earlier this year at the Brussels airport, right down to the taxi that carried the men to their target: Inciting panic and then taking lethal advantage, three suicide attackers unleashed a deadly tide of bullets and bombs at Istanbul's Ataturk Airport, leaving 42 dead.

Authorities blamed the Islamic State in Iraq and Syria (ISIS) for the bloodbath late Tuesday, a co-ordinated assault on one of the world's busiest airports and on a key NATO ally that plays a crucial role in the fight against the extremist group.

There was no immediate claim of responsibility by the militant group.

One official said authorities are going through surveillance footage and interviewing witnesses to establish a preliminary timeline and details of the attack. "It is a jigsaw puzzle," said the official.

AFP_CK25D

A mother of victims reacts outside a forensic medicine building close to Istanbul's airport on Wednesday. (Bulent Kilic/Getty Images)

Although the attack took a heavy toll, the assailants were initially thwarted by the extensive security on the airport's perimeter, Turkish officials said.

"When the terrorists couldn't pass the regular security system, when they couldn't pass the scanners, police and security controls, they returned and took their weapons out of their suitcases and opened fire at random at the security check," Turkish Prime Minister Binali Yildirim said.

TURKEY BOMB ATTACK AFTERMATH

An armed Turkish policeman patrols behind a police line after multiple suicide bomb attacks at Ataturk airport in Istanbul, on Wednesday. (Sedat Suna/EPA)

One attacker detonated his explosives downstairs at the arrivals terminal, one went upstairs and blew himself up in the departure hall, and the third waited outside for the fleeing crowd and caused the final lethal blast, two Turkish officials said, speaking on condition of anonymity because they weren't authorized to speak about the investigation publicly. None of the attackers were Turks, a third official said.

Witnesses describe panic and chaos

As the chaos unfolded, terrified travellers were sent running first from one explosion and then another. Airport surveillance video showed a panicked crowd of people, some rolling suitcases behind them, stampeding down a corridor, looking fearfully over their shoulders.

Other surveillance footage posted on social media showed one explosion, a ball of fire that sent terrified passengers racing for cover. Another showed an attacker, felled by a gunshot from a security officer, blowing himself up seconds later.

GRAPHIC WARNING: Video of Bombing at Turkish airport0:45

"So, what can we think? We cannot think anything," said Ali Batur, whose brother died. "A terror attack might happen everywhere, it happens everywhere. This terror trouble is also in our country. If God permits, we will get over this in unity and solidarity."

Cihan Tunctas had just disembarked from a flight from Azerbaijan when he heard the sound of gunfire.

"Then the bomb exploded. We were at the exit and … the roof collapsed on our heads," Tunctas said. The group tried to escape, but their path was blocked by the arrival of a second attacker.

"Two of the security guards noticed him. They walked toward him. Just as they were walking toward him, I turned that way. They just caught him and at that moment he detonated the bomb."

Guns and grenades

Investigators later found a Kalashnikov assault rifle, a handgun and two grenades on the bodies, according to the state-run Anadolu news service. Raids at two addresses also uncovered encrypted organizational documents and computer files, the news agency said.

Victims in Tuesday's attack included at least 13 foreigners, and several people remained unidentified Wednesday. The Istanbul governor's office said more than 230 people were wounded and dozens remained in critical condition.

CBC News has learned at least one Canadian is among the injured.

Turkish officials say foreign nationals killed in the blasts were from Saudi Arabia, Iraq, Ukraine, Iran, Uzbekistan, Tunisia, Jordan and China. 

"Consular officials are in touch with Canadian citizens in Turkey who have been affected by this incident and stand ready to provide consular assistance as needed," a spokesperson with Global Affairs Canada said in a statement.

Airport reopens

The airport reopened hours after the attack. 

Murat, a tour operator who hung a Turkish flag outside his shop inside the arrivals hall, said Turks' ability to put terrible events behind them was a virtue and born of necessity after decades of fighting extremism.

"Turks are a bit fatalistic, we believe our fate is written on our foreheads," he said. "We know that we can die here or when we cross the street. The best thing we can do is clean up the mess, put things back in order, and get on with our lives."

An information board inside showed about one-third of scheduled flights were cancelled, and a host of others were delayed.

Despite the delays, Europe's third-busiest airport was bustling with passengers and people coming to greet or bid farewell to loved ones on Wednesday, CBC News's Nahlah Ayed reported from the scene.

Still, she said, things were not quite back to normal. 

"There is intense security," Ayed said. "Very, very heavy security."

Signs point to ISIS

CIA Director John Brennan said Wednesday the attack in Istanbul "bears the hallmarks" of the ISIS "depravity."

Turkey has suffered a series of attacks, and the increasing frequency and scale have scared away visitors and devastated the economy, which relies heavily on tourism. The country is a NATO member and key partner in the U.S.-led coalition against ISIS.

An ISIS suicide bomber killed 10 people in Istanbul in January. Another four died there in a blast in March, which was also linked to the group. 

The bustling airport has been seen as a potential target by the extremist group for some time, and previous attacks have put pressure on the government to take action, said CBC's Dorian Jones. 

"Opposition parties are saying not enough resources are going to fighting Islamic State, and too many resources are going to fighting Kurdish rebels … and this attack will again raise the question of the priorities of the government," Jones said from Istanbul.

TURKEY-BLAST/

Men greet each other in front of a Turkish flag and picture of modern Turkey's founder, Mustafa Kemal Ataturk, at the Istanbul airport following Tuesday's attack. (Goran Tomasevic/Reuters)

The prime minister called for national unity and "global co-operation" in fighting terrorism.

"This [attack] has shown once again that terrorism is a global threat," Yildirim said. "This is a heinous planned attack that targeted innocent people."

Dozens of anxious friends and relatives waited early Wednesday outside Istanbul's Bakirkoy Hospital.

"You can hear that people are wailing here," said Serdar Tatlisu, a relative of a victim. "We cannot cope anymore, we can't just stay still. We need some kind of solution for whatever problem there is."

With files from CBC News