Police say an officer was seriously injured when a rockslide hit his car at the base of Cypress Mountain on Friday evening.
The officer was on routine patrol around 5:30 p.m. on the 3700 block of Cypress Bowl Rd., when a rockslide came across the roadway, hitting his vehicle and a civilian car.
The officer was brought to hospital and is expected to make a full recovery, said Sgt. Mark McLean with the West Vancouver Police.
"He has sustained a very large laceration to his head and he is now recovering from home," McLean told CBC News in an interview.
McLean said the occupants of the civilian vehicle were uninjured and did not require medical treatment.
Cypress Bowl Road remained closed for several hours while debris was cleared before re-opening in both directions just before midnight, according to a Tweet by DriveBC.
Police say there are no further threats to drivers in the area.
'Freezing-and-thawing cycle' behind rockfall
Rockslides are more common during the fall and spring, when temperatures drop below zero at night but rise during the day, according to geologist Brent Ward.
Ward, co-director of the Centre for Natural Hazards Research at Simon Fraser University, says when snow melts during the day, water slips into cracks in rocks.
When temperatures drop at night, this water freezes and expands, which can cause rocks to fracture and trigger a rockfall.
"It's this freezing-and-thawing cycle that really triggers a lot of rockfall."
Drivers should not stop beside rocks that have fallen on the road if they come across it, Ward says, because this could indicate more rocks falling.
"There's a lot of work done across the province to keep people safe, but we have so many kilometres of highway," he said.
"It's really hard to keep all the rocks off the road so people do need to be alert while they're driving."