An FBI agent was killed and two other troopers were wounded Thursday while responding to a fire at a high-rise building on Interstate 35, the agency said.

The Texas Department of Public Safety said it was investigating the cause of the fire at the apartment complex in the town of Hays, about 40 miles (65 kilometers) south of Dallas.

The agency said it’s not known if the deaths are related to the incident.

The Associated Press was unable to reach a representative of the agency for comment.

The fire broke out at about 4:40 p.m. in the apartment building.

It was not immediately clear what caused the fire.

The building has several units that are equipped with fire extinguishers, according to the department.

Officials said the building had been empty for weeks before the incident, although the building was used as a housing for several residents and visitors.

“There was no indication of criminal activity, but there was no reason for this,” Sgt. Pete Gallegos, a Hays Fire Department spokesman, told the AP.

Authorities are investigating the death.

Hays is about 70 miles (105 kilometers) northwest of Dallas and about 110 miles (180 kilometers) northeast of Fort Worth.

Texas Gov.

Greg Abbott declared a state of emergency for Hays on Wednesday.