TV footage showed a number of bodies strewn around the bus wreckage with police officers nearby. The van was an unrecognizable pile of smashed white metal.
The bus veered off the Skyway, as the elevated road is called, and crashed onto the van 9.6 meters (32 feet) below in suburban Paranaque city at dawn, said police Superintendent Elizabeth Velasquez.
It wasn't immediately clear what caused the accident but the highway was wet from rain, said Ivy Vidal, a spokeswoman from Skyway Operations and Maintenance Corp.
Irene Sisperes, a motorist who witnessed the accident, said she was driving with her daughter at 80 kilometers per hour (50 mph) when the bus overtook her car. She estimated that the bus was traveling at between 100 kilometers per hour (62 mph) and 110 kph (68 mph).
She said it was still dark and it was raining when the accident happened.
"After a few meters, I saw the bus fall and I shouted, 'The bus fell, the bus fell'," she told DZMM radio, adding there were no other cars nearby.
Sisperes said she saw the damaged railing of the highway and some debris and reported the incident at the toll gate.
Velasquez earlier reported 21 died and 20 others were injured but later said there appeared to have been double counting amid the confusion. She said she was verifying reports 17 perished and a several others were injured.
Angelo Dequina, an employee of a funeral parlor, said 17 bodies from the accident were brought to their mortuary from hospitals and from the crash site.
Calls to five hospitals where the victims were rushed showed at least 16 people injured from the accident have been admitted.
Velasquez earlier said the van's driver was killed and the bus driver was in serious condition in a hospital. But Dr. Carmencita Solidum, medical director of the Paranaque Doctors' Hospital, said the two drivers were among the 10 injured who were at her hospital.
The bus driver was critically injured and but the van driver had minor injuries, she added
Ryan Bresa, a passenger who survived, said the bus may have been traveling too fast and the driver to tried control the vehicle's swerving before it fell from the highway.
Winston Ginez, chairman of the government's Land Transportation, Franchising and Regulatory Board, said all the 78 buses of Don Mariano Transit Corp. have been ordered suspended for 30 days.
Two years ago a bus from another company also fell from the Skyway near the same area, leaving three people dead and four others injured.
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