Imperial Oil is investigating an electrical failure at its Sarnia chemical plant this morning.
Company spokesman Jon Harding says a power failure at the Chemical plant trapped seven workers in an elevator for just over two hours.
It happened around 9:15am and the workers were freed just before 11:30am.
No injuries are reported and the exact cause of the electrical failure is still unknown.
Emergency sirens at the site were sounded just before 9:30am. Sarnia emergency services also responded.