LONDON (AP) — Social media users in London are buzzing about an apparent swarm of flying insects that has descended on one part of the city.

Videos posted to Twitter Tuesday show people ducking as the insects descend on Greenwich in southeast London. It’s not clear what the bugs were or why they appeared in unusual numbers. Some say they’re bees, but others describe them as wasps.

Transport for London, which oversees public transport in the capital, posted a picture from a traffic camera showing large numbers of the insects collecting on a traffic light, and warned drivers that a pedestrian crossing was “partially obstructed by bees.” It warned: “Please approach with caution.”

London police didn’t immediately return a request for comment on whether they’ve received reports on the insects.