FORT WORTH, Texas — The Fort Worth Fire Department said three of its firefighters were injured while battling a house fire Monday evening.

The department, in a post on Facebook, said crews arrived at a house on East Cannon Street before 6 p.m. to find fire already venting through the roof of the two-story home.

As firefighters were combating the blaze, fire conditions changed dramatically, the department said.

The incident commander called for the evacuation tone to be sounded and for crews to prepare for defensive operations.

It was then, the department said, that a “mayday” was called as two firefighters bailed out of a second-story window. The emergency prompted a second fire alarm.

The two firefighters who bailed as well as a third firefighter were injured. They were taken to Parkland Hospital.

There was no immediate update about their conditions.

The cause of the fire is under investigation.