NEW YORK (AP) — The driver of a New York City bus that plunged off a bridge blamed the dramatic crash on mechanical failure, saying Saturday that the tandem vehicle “just took off” as he slowed into a turn.

Everton Beccan, 55, disputed the Metropolitan Transportation Authority’s assertion a day earlier that he had refused to submit to a drug and alcohol test at the hospital.

“There’s no reason for me to refuse a drug test,” Beccan, who broke his jaw in late Thursday’s crash, said at a news conference following his release from the hospital. “I’m just thankful that no one lost their life.”

The MTA on Saturday released an internal document that says Beccan refused three times to submit a urine sample to the transit agency. The test Beccan ultimately took was done by the hospital and wasn’t conducted until several hours after the crash, the agency said.

Transit officials said Friday they had been concerned by Beccan’s failure to submit to the test even after he passed an alcohol breath test. The MTA said the driver has been “withheld from service without pay” amid the investigation.

“This is obviously troubling,” said Patrick Warren, the MTA’s chief safety and security officer.

Beccan said the results of his drug test are pending.

He offered a harrowing account of the articulated bus plunging 50 feet onto a highway ramp near an interchange of the Cross Bronx and Major Deegan expressways.

The crash happened at a turn he has made “hundreds of times” along his regular route, he said, adding he lost control of the bus after easing up on the gas pedal. “The bus just accelerated,” he said. “The bus just took off on its own.”

As the crash unfolded, Beccan said, he was thinking of the passengers’ safety and his own. He said he “helped who I could help” and called 911.

“Everybody was just screaming,” Beccan said. “Everybody was in a panic.”

Seven passengers suffered minor injuries after one part of the bus plunged onto the access road. The other half remained on the bridge. No other vehicles were involved.

The MTA said Saturday that Beccan was driving “almost five times the allowable speed for a bus making the turn being attempted.” The agency said investigators “have thus far identified no mechanical cause for the failure to remain on the road and to travel at allowable speed for the conditions,” citing the bus’ on-board event recorder.

Beccan has more than 11 years of service and a good safety record, the MTA said.