Three or four men hijacked a Mexican airliner carrying 104 passengers. The plane is sitting on a runway at the Mexico City airport. A "square box" has been found onboard, and all passengers have reportedly exited the plane.

Update 2: "As many as eight" hijackers were arrested. Multiple reports say one of them spent the whole flight clutching a Bible. One passenger says the hijacker was "a Bible fanatic from Bolivia." So, there you have it: now we have to watch out for Bolivian Bible-thumpers.

Update: The crew is now free. Calderon is on his way back to Mexico City. The plane was flying from Cancun to Mexico City (and then Cabo and then San Diego) when it was hijacked by three (still possibly four) Bolivian men. Passengers largely didn't know the plane had been hijacked until it landed and was surrounded by Federal Police. The Federales stormed the plane and took some passengers off. At least one person been detained, and three men have been brought off in handcuffs, according to police. If that's true, this is probably over. But it is still unclear how many people are on that plane.

According to reporting on Fox, the hijackers were four Colombian men (CNN says possibly Bolivian), they claimed to have a bomb, and they demanded to talk to Mexican President Felipe Calderon. It has not been officially confirmed that all the passengers have been allowed to leave, and Mexican federal police and military personnel are on the scene.

Early reports suggest this is drug cartel-related. The pilots and flight crew are reportedly still on board.