The National Transportation Safety Board sent a team to investigate a charter bus crash off Interstate 15 that killed three passengers and injured 18 others, the federal agency said Sunday.
The agency, which investigates transportation crashes, said on Twitter that “a team of four” was sent to the scene of the crash in the Pala Mesa area in northern San Diego County, just south of State Route 76, authorities said.
The crash occurred amid rainy conditions when the driver swerved and lost control of the bus in the southbound lanes of the freeway about 10:20 a.m. Saturday, officials said. The bus slid down an embankment and landed on its roof.
Some of the 21 passengers, a mix of adults and children, were thrown from the bus, while others were trapped inside, authorities said. Some crawled out on their own.
Three women, one who was pinned under the bus and two who were pulled from inside, died before they could be taken to a hospital, authorities said. Their names were not released.
Eighteen others were taken to area hospitals, authorities said.
The bus driver, a man from Whittier, suffered minor injuries and initially remained at the scene, said California Highway Patrol Officer Mark Latulippe. He was later taken to a station for questioning.
The driver, whose name was not released, voluntarily submitted a blood sample, which is standard in such investigations. However, drugs and alcohol are not suspected of being a factor in the crash, authorities said.
The charter is owned by Executive Lines, a company based east of Los Angeles. The U.S. Department of Transportation website shows a clean record for the company, which passed all inspections in the last two years.
Latulippe said Saturday that it was too early to determine what extent weather played a role.
The bus, which was hauled up the embankment by a heavy-duty tow trunk, was taken to a CHP evidence yard. Latulippe said it would be examined for possible mechanic failures such as steering and braking issues.
City News Service contributed to this report.