LOS ANGELES (CBSLA.com) — Federal agents and arson investigators are expected to enter the site of a massive construction fire in downtown Los Angeles Wednesday morning while firefighters continued to monitor and douse several hot spots.

The fire, which was being treated as “suspicious,” was reported about 1:20 a.m. Monday at the Da Vinci Complex on North Fremont Avenue and lit up the L.A. skyline.

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Late Tuesday, firefighters sought to preserve potential evidence for the anticipated 20 experts from the Bureau of Alcohol, Tobacco, Firearms and Explosives, who were expected to arrive Wednesday.

“ATF will come in, will be able to use their labs. We also have our canines, the larger pool of specialists to be able to determine the cause,” Erik Scott, a spokesman for the Los Angeles Fire Department, told KCAL9’s Peter Daut.

The massive fire destroyed seven stories of apartment units under construction and damaged three nearby high-rise buildings, blowing out windows.

The intense heat also melted freeway signs and temporarily shut the adjacent 101 and 110 freeways.

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Investigators said the speed of the flames has raised questions. They’re now interviewing witnesses and some of the 250 firefighters who helped put out the blaze, which left behind tens of millions of dollars in damage.

A news conference with ATF investigators is scheduled for 11:30 a.m. Wednesday.

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