A car accident involving a Sound Transit bus and an SUV left two dead Monday night at an Interstate 405 Kirkland exit.

Robert H. Rotta, 76, died at the scene when a Sound Transit bus, exiting northbound 405 in the carpool lane, slammed into the 2010 Ford Escape he was in on Northeast 128th Street overpass, according to the Washington State Patrol.

Elizabeth E. Rotta, 75, who was also in the SUV, died from her injuries early Tuesday morning at an area hospital.

A third passenger in the SUV, Kirkland resident Kendall L. Rotta, 51, was transported to Harborview Medical Center with undisclosed injuries. All three were wearing their seat belts.

There has been no conformation of the relation between the passengers in the SUV.

Passengers on the bus called 911 at around 9:30 p.m. to report the bus had hit an SUV, according to Washington State Patrol trooper Julie Judson. Some of the bus riders were reported to have injuries.

“One was transported [to the hospital] but the rest had minor injuries and were treated at the scene,” Judson said.

The bus, a 2008 Gillig, finally came to a stop on the carpool on-ramp to northbound 405.

There were about 35 passengers on the Route 535 bus, which runs from Bellevue to Lynnwood.

The bus driver, who is now on paid administrative leave, told authorities that his brakes failed or had mechanical failure. Judson said that he was being “very cooperative” with the investigation. There was also no sign of drugs or alcohol involved.

“We are still standing by to find out the results of the vehicle inspection,” Judson said.

Judson said that she could not remember another incident where a Sound Transit bus had mechanical failure.

“I imagine they are very rare,” said Judson, who pointed out that there has been no confirmation that the bus had a mechanical failure.

Judson said the cause of the accident is still under investigation.