A motorcyclist was killed and a vehicle burst into flame in a multi-car crash on northbound Interstate 680 in Walnut Creek Sundayevening, according to the California Highway Patrol.

The crash, which occurred on 680 just south of Rudgear Road just after 5:45 p.m., involved four vehicles including a motorcycle, according to CHP Officer John Fransen.

Details of exactly what happened remain unclear, but one vehicle, a Nissan 350Z, burst into flames after the crash, Fransen said.

Witnesses told investigators that the motorcycle and another vehicle were driving recklessly before the crash, Fransen said. The description of the second vehicle was unavailable and it is unclear whether it was one of those involved in the crash.

The motorcyclist was killed, but Fransen could not say whether other people were injured.

Northbound Interstate 680 was closed by the crash but reopened just before 8 p.m.

The crash remains under investigation and investigators are asking anyone who witnessed the crash or the events leading up to it to call (925) 646-4980.