A man climbed KTLA's iconic tower on the Sunset Bronson Studios lot early Wednesday evening, leading police to shut down Sunset Boulevard in Hollywood.
The man - wearing what appeared to be a green hooded Boston Celtics sweatshirt - began climbing the tower around 4:45 p.m.
He was still on the tower, some 80 feet up, more than an hour later.
At one point, he appeared to be smoking.
Aerial video from Sky5 showed the Los Angeles Police Department and Fire Departments were responding, with multiple fire engines and ambulances on scene.
Three inflatable air cushions were placed at the base of the white metal tower.
Sunset Boulevard is closed from the 101 Freeway west to Gower Street.
Another individual climbed the structure in 2011, also prompting an emergency response.
The tower is at the corner of Sunset Boulevard and Bronson Avenue in the heart of Hollywood.
The 160-foot radio tower was, in 2014, taken apart and relocated to that site - its original location - amid construction on the lot.
It reappeared in March 2015.
Originally erected in 1925, the tower is behind a fence.
KTLA's call letters have been displayed on the tower for more than six decades.
Check back for updates on this developing story.