Two workers at an Ontario, Canada, swine barn were seriously injured in an explosion on Sunday afternoon, according to

The incident occurred before 12:30 p.m. at a farm near Seaforth. Authorities said the two men were pumping manure from the barn when the explosion occurred.

Dann Eedy, 25, and Joshua Purdy, 15, were transferred by air ambulance to a nearby hospital in London, Ontario.

Officials of Ontario’s Ministry of Labour and the Ontario Fire Marshal’s office are assisting with the investigation. Police said the cause of the explosion hasn’t been determined.

Read more about dangers of manure pumping and recommended precautionary steps.