A Metro Transit driver whose bus crashed along Nicollet Mall last week died of natural causes after collapsing at the wheel.

The Hennepin County medical examiner’s office said John L. Senior Jr., 58, of Edina, “suffered a sudden collapse.”

A Metro Transit spokesman, Drew Kerr, said Senior, 58, began working at the agency in 2013.

When he last renewed his driver’s license, the 6-foot-1 Senior listed his weight as 350 pounds. He joined the Edina Fire Department in 1980 but lost his job in 1988 after his weight reached 400 pounds.

His weight prevented him from fastening the belly strap of a self-contained breathing apparatus, considered an essential piece of equipment for firefighters. He also said he had difficulty climbing a ladder while wearing standard firefighting gear.

Senior fought to be reinstated, ultimately failing to win over the state Court of Appeals in 1996.

Kerr said in an e-mail on Sunday that “all operators must be medically certified by a Metro Transit-approved physician before they are hired and are required to renew their medical certifications at least every two years thereafter. These medical certifications are a (Department of Transportation) requirement to hold a Commercial Driver’s License.”

Metro Transit also verifies that operators have current, valid driver’s license daily, he said.

“Metro Transit is committed to the health and well-being of all employees and offers an extensive wellness program, including exercise equipment at all bus garages,” Kerr said.

Asked if Metro Transit was aware that Senior had lost his fire department job over weight issues, Kerr responded by email:

“Employment history,” Kerr wrote, “including the reasons an individual left a prior job, is also a consideration in the hiring process. Here, too, judgements are made on a case-by-case basis.”

The southbound bus veered off Nicollet Mall Friday, hit a lamppost, trash bins and scraped the WCCO building before coming to a stop near Peavey Plaza.

A passenger on the bus was slightly hurt as was a bicyclist clipped by the bus.

Passengers said they could see the driver suffering a medical episode before the bus went out of control. The crash occurred shortly after 10 a.m., and Senior died about an hour later at Hennepin County Medical Center.

Staff writer Randy Furst contributed to this report.