Police headed for the Pentagon this morning, after gunshots were heard and several bullets struck the massive building in Northern Virginia, causing minor damage.

No one was hurt and no suspects were immediately apprehended, but police shut some of the road and pedestrian entrances when a civilian said he thought he heard shots around 5 a.m. at the south side of the building.

The Washington Post reported, “A police sweep confirmed the structure had been hit, but it was not clear how many shots were fired or what type of weapon was used.”

On Monday, bullet holes were discovered in several windows at the National Museum of the Marine Corps in Triangle, Va., which is about 30 miles south of the Defense Department headquarters.

This was not the first open fire at the Pentagon, as back in March; a gunman was shot by police and later died after he opened fire at a Pentagon security checkpoint, wounding two officers.