An aircraft about the size of a car crashed into Beijing’s tallest building on Friday, witnesses told Reuters. Police closed roads around the skyscraper, and authorities did not provide information about the crash.

The building is known as CITIC Tower, also called China Zun. It is a 108-storey skyscraper in Beijing’s central business district and the headquarters of CITIC Group, a state-owned conglomerate.

Witnesses reported a heavy police presence at the site, with some approach roads shut to cars. Reuters reported that some people were prevented from taking pictures, and others were asked to delete footage they had captured while police ushered people away from the area. Several fire trucks were also seen near nearby roads.

Damage was reported on the exterior of the tower: two glass panels on a high floor were damaged. There was no immediate official comment from authorities.

Accounts from people at the scene varied in what they saw. A courier who said he rushed to the area around 6 p.m. local time reported hearing a loud crash and said he saw what looked like the aircraft stuck in the building. He said the noise was “louder than fireworks.” He added that he deleted video footage out of concern about police stopping him.

Another courier said he went to the scene after seeing unverified social media images that appeared to show wreckage on a road next to the building. Reuters also reported that social media posts relating to the incident were quickly removed.

One office worker in a nearby building said she saw a blue tarp covering a large object on the roadside. It was not immediately clear whether the crash was deliberate or accidental.