The bus was travelling through the town of Juvisy-sur-Orge southeast of the French capital when it veered off the road and fell into the Seine, prosecutors told AFP.

"The driver and three other people were on the bus," prosecutors added. "They have all been rescued," they said, adding that the police have opened an investigation.

Officials did not provide details on the condition of the rescued people. The bus was being operated by a trainee in the final stages of her instruction, said a spokesman for the IDFM transport authority. Both she and her supervising driver tested negative for drugs and alcohol, he said. The bus was scheduled to be recovered from the water later Thursday, he added.

Several rescue boats, a drone and helicopters were deployed as part of a recovery effort. Sixteen fire engines with more than 30 firefighters and dozens of police officers were involved as well, the prefecture said

The bus was completely submerged under water near a bridge while the parked car struck by the vehicle also ended up in the river, an AFP journalist reported.

A witness told AFP she saw the bus sweep the other vehicle with it as it went over the edge and into the water. "Instead of veering to the right, the bus went straight on and dragged a car down with it," said Elisabeth, a 55-year-old conservatory employee, who asked that her last name not be used. Bystanders then rushed to a nearby barge, and life rings were thrown out before emergency services arrived, she added.

Another witness said he feared a bomb had gone off when he heard the loud crash. "I felt like every firefighter in the department was there," said Amine, a 19-year-old medical student, without providing his last name.