Two bikers were killed Sunday in a crash on the Maine Turnpike.

AUGUSTA (AP) — Maine police have determined the cause of a double fatal motorcycle crash that happened during the United Bikers Toy Run last weekend.

The Portland Press Herald reports the crash occurred on Interstate 95 in Augusta. Police say the chain reaction crash on Sunday started when 58-year-old Jamie Gross drifted into the passing lane and was struck by a pickup truck driven by 67-year-old William Nusom.

Nusom tried to avoid the motorcycle, struck the median guardrail and hit other motorcyclists participating in the Toy Run.

Gross died at the scene and 25-year-old Aaron White-Sevigny died at a hospital. Two other motorcyclists who were riding the same bike were taken to a hospital.

Nusom and his 99-year-old mother were treated at a hospital.

State police continue to investigate the crash.