A 52-year-old Syar Industries truck driver was killed in an industrial accident at the company’s Vallejo sand and gravel business on Lake Herman Road.

William Hall, 52, of Vallejo, died on Tuesday when the 75-ton truck he was driving at the site backed down a 20-foot embankment, according to California Occupational and Health Safety Administration spokeswoman Kate McGuire.

The trailer of the truck flipped over and landed on the cab, crushing Hall, she said.

McGuire said CalOSHA is investigating the accident to determine if there are any violations to the state health and safety codes.

She said the investigation could take three to four months to complete.