Some 150 firefighters have extinguished a fire that damaged the roof and attic of the Czech National Museum in the capital, Prague.

Firefighters spokeswoman Pavline Adamcova says the fire broke at about 1.30 a.m. (0030 GMT) Friday and it took the crews about two hours to get it under control. Adamcova says some 200 square meters (2,150 square feet) of the roof were damaged.

National Museum director Michal Lukes says it is not immediately clear what caused the fire. The overall damage is being assessed.

The monumental building that dates to 1891 is located at the top of downtown Wenceslas Square. It is in the middle of a major refurbishment and there are no collections inside. It is due to reopen in 2018.