By KEN MILLER and PAUL J. WEBER (Associated Press)

Fire broke out Friday morning at a state prison in Texas, forcing more than 650 inmates to evacuate but injuring no one, an official said.

The fire, the cause of which isn’t yet known, appeared to be confined to the attic and third floor of the administration building and the attic of a unit that houses inmates, said Amanda Hernandez, a spokesperson for the Texas Department of Criminal Justice.

The inmates had initially been moved to other areas of the prison in Huntsville, about 65 miles (105 kilometers) north of Houston. But Hernandez later said about 400 of the displaced inmates will be moved to other facilities across the state.

The fire was contained, but firefighters were “still chasing small fires in some concealed spaces,” Huntsville Fire Chief Greg Mathis said.

The cause will be investigated once it is completely out.

All inmates and staff are safe and accounted for, Hernandez said.

Huntsville is the headquarters of the Texas prison system, which houses more than 130,000 inmates, more than any state in the U.S.

The system has come under scrutiny over the conditions of its roughly 100 lockups, including the absence of full air conditioning in most facilities and concerns over fire prevention.

A report by the State Fire Marshal’s Office in 2021 noted that “most of the units’ fire alarm systems aren’t functioning properly.”

Inspectors that year found nearly 1,700 violations, according to the report, which also noted that steam kettles were often used as fryers. There were no records of testing fire doors, dampers or standpipe systems.

In May, Texas lawmakers approved giving the prison agency millions of additional dollars for repairs and improvements, though the extra funding does not kick in until the next budget cycle, starting in September.

The 174-year-old Huntsville Unit was built in 1849 and is nicknamed the Walls Unit because of its red brick walls. It currently houses about 1,600 prisoners with space for about 1,700.

The prison is where condemned inmates are executed, but the death chamber was not affected by the fire, according to Hernandez.

The fire is not expected to affect the execution schedule, Hernandez said. The next one is set for Oct. 10, when Jedidiah Murphy is to be put to death for killing a 79-year-old woman in 2000.