A student at a suburban Denver high school set himself on fire in the school's cafeteria today and is in critical condition, authorities said.

A female teacher was treated for minor cuts when she broke a pane of glass to access a access a fire extinguisher and a school custodian used the extinguisher to put the fire out, Westminster Police Investigator Cheri Spottke told ABC News.

The student, who is 16 but otherwise not identified, is in critical condition with severe burns, Spottke said.

The incident happened at 7:12 a.m. in the cafeteria of Standley Lake High School in Westminster, Colo. Police said students were present in the cafeteria at the time, but none were injured.

Investigators do not know why the boy set himself on fire, and are talking to his friends, school employees and his parents for clues, Spottke said. They are also reviewing surveillance video from inside the school cafeteria, police said.

Police would not comment on whether the boy said anything before lighting himself on fire, or if he had doused himself in gasoline or any other accelerant.

School is closed today and Tuesday, and counselors are being brought in to help, police said.