MEXICO CITY – A jetliner from the beach resort of Cancun was briefly hijacked as it landed in Mexico City on Wednesday. The hijackers released all passengers shortly before federal police stormed the plane, and the crew emerged unharmed moments later.

Police, who did not fire a single shot, led as many as eight handcuffed men away from the airplane, which was isolated at the end of a runway in an area designed for emergencies. The hijackers' motive was unclear, though Mexican news media initially identified them as Bolivians demanding to speak with Mexican President Felipe Calderon.

U.S., French and Mexican citizens were among the 112 passengers and crew on Aeromexico Flight 576, according to a U.S. official who had been briefed on the situation. The official was not authorized to discuss the case and spoke on condition of anonymity.

Mexico's transportation and communications secretary, Juan Molinar, said there was no bomb on the airplane, although some passengers said one of the hijackers held a package that resembled an explosive device, and a bomb squad was later seen near the airplane.

The attorney general's office said it was opening an investigation into terrorism and kidnapping but did not specify how many people could be charged.