A small government plane crashed into rush hour traffic in Mexico City on Tuesday, killing all eight people on board, including Mexico's interior minister.
Mexico City Mayor Marcelo Ebrard said others may have died on the ground.
"It's likely that we will find other bodies," Ebrard told the Televisa news network.
Mexico's transportation ministry confirmed that Interior Minister Juan Camilo Mourino was in the Learjet 24 plane at the time of the crash, as was former assistant attorney general Jose Luis Santiago Vasconcelos.
Aviation officials are investigating the cause of the crash.
The crash set two dozen cars on fire and wreckage was spread across a wide area in Mexico City's wealthy Lomas de Chapultepec neighbourhood. Emergency workers scrambled to douse the fires and keep spectators away.
More than 40 people on the ground were injured.
At least 1,800 people were ordered to flee offices in the area. The plane's wreckage came to rest just metres from tall office buildings and Ebrard said many more people would have died had the plane hit one of the towers.
Mourino, Santiago and a group of advisers had been flying home to Mexico City from an event in the city of San Luis Potosi when the crash occurred.
Santiago was best known for his efforts to seek extraditions against drug traffickers, work that saw him targeted by at least one planned assassination attempt.
Mourino, meanwhile was one of President Felipe Calderon's closest advisers, overseeing the country's security.
"With his death, Mexico has lost a great Mexican, intelligent, loyal and committed to his ideals and his country," Calderon told a news conference. "I ask all Mexicans that they don't allow any event, no matter how difficult or painful, to weaken them in the pursuit of a better Mexico."
According to Bloomberg news service, Mourino, 37, had previously served as a deputy energy minister and congressman under former president Vicente Fox. He became interior ministry in January and previously ran Calderon's campaign for president.
Calderon had assigned Mourino to crack down on drug trafficking violence that has killed more than 4,000 people this year in Mexico. Mourino also led negotiations with opposition party members on Calderon's plans to open the state oil industry to private and foreign investment.
But Mourino's career had also been touched by scandal. According to the New York Times, he was accused of steering lucrative contracts with the state oil monopoly to his family trucking business.