City officials Wednesday evening said all tests of the steam leak that continues to shut down a section of midtown Manhattan have come back negative for asbestos, but Mayor Eric Adams said the cause of the leak is still under investigation.

“Out of an abundance of caution, we advise residents in the area to wear masks, keep their windows closed and stay indoors,” Adams said.

In a statement, Con Edison said crews will remain at the site around the clock and are working to wash debris from the streets and building facades in the area.

Zach Iscol, commissioner of New York City Emergency Management, said he expects operations to continue for “at least a few days, possibly more” as crews shift to the next phase of the operation and determine the scope of the problem.

“We have a pretty big area that we need to clean, the light rain today and the rain we’re going to have overnight will also help, but we have started cleanup operations, starting with Third Avenue,” Iscol said.

As of 3:15 p.m. Wednesday, Third Avenue was closed between East 42nd and East 54th streets while officials continued work at the scene. Second Avenue was also closed between East 50th and East 57th streets; East 51st to East 54th streets were closed between First and Third avenues; East 51st to East 53rd streets were closed between Third and Lexington avenues; and East 52nd Street was closed between Lexington and Park avenues, the NYPD said.

Business owners in the area said they weren’t happy about losing out on foot traffic because of the closures.

“People from the south can’t walk up here because the street is closed off. There’s hazmat tents up and police, firemen all over the place so it’s really kind of quiet. The only people coming in are the workers,” said Tom Citro, owner of Louie’s Chicken.

The FDNY said it received a call shortly after 5:30 a.m. Wednesday about excessive steam emanating from the area. Police said Con Edison had been working at East 52nd Street and Second Avenue when steam started leaking.

Department of Environmental Protection personnel arrived at the scene and worked with Con Edison employees to stop the steam leak. In a statement, Con Edison said it was responding to “a possible release of asbestos from a steam main vent stack.”

NYCEM urged commuters to consider taking alternate routes to avoid the area and to expect traffic disruptions while officials conduct their investigation.

N95 masks are being made available to area residents who are concerned about air quality. Police escorts in and out of nearby buildings will also be offered to those who ask, according to NYCEM.