DriveBC says the road is closed in both directions at Kennedy Lake due to the blockage, adding late in the day there would be no update until 6 a.m. Friday.
The Ministry of Transportation said the failure was a result of an accident during construction on the highway.
“During a scheduled blast overnight at the Highway 4/Kennedy Hill Safety Improvements project, rockfall from the blast resulted in a failure of the road,” said a ministry spokesperson in an email.
“The contractor was following an approved plan for the blast but larger than anticipated rockfall resulted in a portion of the road being impacted making it unsafe for the ministry to open the highway at this time.”
The ministry said the road was closed at the time of the blast. It said geotechnical engineers were on site and had determined it was safe to begin repairs.
The ministry said crews worked through the night and would reassess the situation at first light.
“We have no way to drive out now. We’re fortunate to have an airport, so there are ways that people can get out. But usually it means you just have to hang tight and wait,” said Tofino Mayor Josie Osborne.
“If you’re a visitor who’s waiting to come out for your hotel reservation or maybe you were staying here and you’re trying to get home now it’s obviously a huge inconvenience.”
The province is in the midst of a $38-million safety upgrade to the Kennedy Hill portion of Highway 4, for work on a 1.5 kilometre stretch adjacent to Kennedy Lake.
The work includes widening shoulders and adding a new rest area.
Osborne said the work is badly needed.
“It’s just over one kilometre that literally hangs on the side of a cliff next to Kennedy Lake and its got a series of tight curves with poor sight lines and very, very slow travel,” she said.
“So it’s been an area that’s been targeted for some safety upgrades for some time.”
DriveBC had previously listed overnight road closures and delays along the very same stretch of road due to planned construction work.
Work was planned Thursday morning from 1-4 a.m. and 5-7 a.m.