CHICAGO (AP)—Ninety windows shattered or cracked at the Sears Tower when wind gusts up to 56 mph blew debris into the world’s tallest building early Monday, forcing police to temporarily close several streets.

Police and officials at Sears, Roebuck and Co. said there were no reports of injuries from falling glass.

The windows, about 5 feet wide and 8 feet tall, began shattering and cracking about 3:30 a.m. when wind gusts of up to 56 mph were recorded in the area, said Ernest Arms, a spokesman for Sears, whose corporate headquarters are in the 110-story building.

A survey of the building’s 16,000 windows later Monday morning by building engineers found that 90 panes were broken or cracked, apparently by wind-whipped gravel and other debris, said Gordon Jones, another Sears spokesman.

Jones said company officials did not have a monetary estimate of damages caused by the high wind.

“They’re not blown out,” Arms said. “What happened is something flying through the air—like a pebble from the roof of another building—hit and broke one window and then others were damaged as (pieces of) that one window came down.”

Jones added that Sears officials don’t know if one or more windows were broken initially by flying debris. “We surmise that one or more would be broken by debris initially and then they would contribute to others breaking,” he said. “We don’t really know—it happened in the dark.”

Arms said the broken and cracked windows were located between the 50th and 88th floors of the 1,454-foot building, the world’s tallest.

Five windows were broken during high winds in April 1984, he said.

Arms said authorities had closed the Franklin Street entrance to the building, restricting employees and visitors to doors on Jackson Street or Wacker Drive.

Chicago Police Patrolman Frank Daio said authorities were forced to block traffic during the morning rush hour on the four streets surrounding the building.