PALO ALTO (CBS SF) — Two repairmen suffered ‘critical, but not life-threatening’ burns Tuesday when a fire erupted inside an elevator shaft inside a Palo Alto building, authorities said.

Deputy Palo Alto Fire Chief Kevin McNally said his agency got a 911 call at 10:40 a.m. reporting a fire alarm inside a mixed-use building at Park Blvd. and Page Mill Rd.

‘One of our units responded to the scene for the report of a fire alarm,’ McNally told KPIX 5. “Upon arrival they found two victims with burns…There was maintenance going on to the elevator shaft that caused flames and burns to the two victims.”

Investigators were on scene trying to determine the cause of the fire. The building was evacuated and no other injuries have been reported.