MANCHESTER, Tenn. (AP) _ A Greyhound bus crashed Wednesday, killing four of the 37 people aboard and prompting Greyhound to halt all service nationwide as a precaution, a company spokeswoman said.

The bus crashed after a passenger slit the driver's throat, another passenger told a Nashville television station. Authorities could not immediately be reached for confirmation.

The bus, No. 1115, was en route from Nashville to Atlanta when it crashed, Greyhound spokeswoman Kristin Parsley said. WTVF-TV of Nashville reported that the crash came near Manchester, 50 miles southeast of Nashville on Interstate 24.

Speaking by cellular phone from the crash site, passenger Carly Rinearson told WTVF that a man who looked to be 30 to 35 years old kept approaching her front seat in the bus and asking what time it was. The man then asked if he could have her seat, Rinearson said. She refused.

Afterward, ``he just went up to the bus driver and, like, slit his throat and the driver turned the wheel and the bus tipped over,'' Rinearson said.

Parsley, the Greyhound spokeswoman, said 37 people were on board.

The Dallas-based company stopped all service as a precautionary measure after the crash, she said. About 1,900 of its 2,300 buses had been on the road when the crash occurred, she said.

She said buses already en route were allowed to continue to their destinations.

She said she could not confirm anything about the reported slashing.

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Greyhound has set up a toll-free phone number for relatives seeking information about passengers 800-884-2744.