One motorist is confirmed dead in a motorcycle crash on northbound U.S. Highway 101 near Third Avenue in San Mateo, a California Highway Patrol officer said.

The CHP closed down lanes one, two and three of northbound Highway 101 due to the crash, which may involve another car, Officer Kevin Bartlett said.

It was not immediately known if there were any other injuries, he said.

The CHP issued a SIG alert at 5:30 a.m. and said the lanes will not reopen until 7:30 a.m. at the earliest, Bartlett said.  

Motorists are advised to use Interstate Highway 280 as an alternate route, Bartlett said.