Houston ? Like a scene from the horror movie “The Birds,” large black grackles are swooping down on downtown Houston and attacking people’s heads, hair and backs.

Authorities closed off a sidewalk after the aggressive birds, which can have 2-foot wing-spans, flew out of magnolia trees in front of the County Administration Building.

An area in front of the Harris County Administration Building in Houston is cordoned off to keep pedestrians away from large black grackles. The birds began swooping down and attacking people's heads, hair and backs earlier this week. It appeared that the birds were protecting their offspring.

“They were just going crazy,” said Constable Wilbert Jue, who works at the building. “They were attacking everybody that walked by.”

The grackles zeroed in on a lawyer who shooed a bird away before he tripped and injured his face, Jue said. The lawyer was treated for several cuts.

It appears that the birds are protecting their offspring. On Monday a young grackle had fallen out of its nest and adult birds attacked people who got too close, Jue said.

Another bird attacked a deputy county clerk.

“I hit him with a bottle,” said Sylvia Velasquez. “The other birds came, and one attacked my blouse and on my back.”

Two women came to help her after she fell to the ground, and the birds attacked them as well. The group escaped by running into the building.

“This is a very Hitchcock kind of story. Very Tippi Hedren,” said downtown worker Laura Aranda Smith, referring to one of the stars of Alfred Hitchcock’s horror movie “The Birds.”