Rescue workers search for evidence and victims of Wednesday's deadly plane crash in the mountains surrounding Islamabad, Pakistan, on Thursday. (Anjum Naveed/Associated Press)

Pakistan marked a day of mourning Thursday for the 152 victims of the country's worst plane crash, as emergency crews continued a grim search for bodies amid thick mud, rain and slippery hillsides.

By Wednesday night, emergency crews had recovered 115 bodies from the wreckage of the Airblue flight, which crashed into the hills outside Islamabad on Wednesday, federal Information Minister Qamar Zaman Kaira said.

Army troops and civilian rescue workers resumed the search on Thursday in the hopes of finding the remaining 37 bodies. The search is difficult because many of the bodies were torn apart in the crash.

Tough conditions also slowed the pace of operations, said Ramzan Khalid, spokesman for the Capital Development Authority, which helps deal with emergencies.

Authorities now believe monsoon weather was a factor in the crash, which killed everyone on board — 146 passengers and six crew members.

But Pakistan's Civil Aviation Authority also said the plane had been ordered to take an alternative approach to the runway, but had veered off course. Finding out why will be a key task of the investigation team, said Riazul Haq, director general of the agency.

"The fact remains it flew where it should not have done," he said.

Relatives mourn

Family members of the Airblue plane crash victims console one another on Thursday after arriving at an Islamabad hospital to identify their bodies. (Faisal Mahmood/Reuters)

Rehan Khan, of Markham, Ont., said his brother, sister-in-law and their children died in the crash. The family, which lived in Pakistan, was on a cross-country vacation when it happened.

"My mother, she is crying, she keeps crying," Khan told CBC News Wednesday. "They all [have] gathered in my house.

"I've grown up there," he said. "I have to be there."

In Islamabad, dozens of relatives and friends of those killed hugged one another outside the city's largest hospital. Many had spent the night camped outside the hospital hoping to receive bodies.

It could take days to identify all the victims with DNA testing because many of the bodies were shredded and burned in the violent crash.

"There is nothing left, just piles and bundles of flesh," said rescue worker Murtaza Khan.

Though many of the dead are believed to be Pakistani, the White House confirmed Wednesday that two Americans died in the crash. As of Wednesday evening, no Canadians had been confirmed dead, according to Foreign Affairs spokeswoman Lisa Monette.

Airbus to aid investigation

The control tower at Islamabad airport lost contact with the Airbus plane as it was trying to land Wednesday morning, said Pervez George, a civil aviation official. Several officials noted the plane seemed to be an unusual distance from the airport, which was some 15 kilometres away.

Raheel Ahmed, a spokesman for the airline, said the plane had no known technical issues, and the pilots did not send any emergency signals. Airbus said it would provide technical assistance to the crash investigators.

The plane's black box flight data recorders have not been recovered. Information extracted from them will be key in determining the cause of the crash. Defence Minister Chaudhry Ahmed Mukhtar and other officials have said the government does not suspect terrorism.

The plane was flying from Karachi, the country's commercial capital.

In other parts of northern Pakistan, heavy rains have washed away streets and battered dams, and are blamed for 28 deaths.

Ten people died when their homes collapsed under the weight of the rains in Peshawar, in the northwest part of the country, officials confirmed Thursday.

With files from CBC News