Monday's massive fire on North Clinton Avenue remains under investigation. Flames destroyed much of the Ridge Clinton Plaza and firefighters say the cause is suspicious. Now, the Rochester Fire Department is getting some federal help.

“Our presence here is not something new," said Christopher Porreca, a Bureau of Alcohol, Tobacco, Firearms and Explosives Team Leader.

Wednesday, the ATF began assisting the Rochester Fire and Police Departments in the investigation of the massive Family Dollar fire on North Clinton Avenue. It started around noon and quickly spread to surrounding businesses.

"ATF is an agency that believes in working cooperatively with our state and local partners as an equal partner," said Porreca.

Federally certified fire investigators, engineers and agents were requested by the city of Rochester to help remove and sift through the debris that was once part of the strip mall, bringing additional resources to Rochester.

"The more people we can bring into an incident, then the quicker we can get to a determination and either move on to the next part or close the investigation,” he added.

"It's been a very seamless melding of the organizations,” said Rochester Fire Chief John Caufield. “Everybody is sharing information. We are working together in teams."

The ATF says they will be here for however long it takes, even working through the Thanksgiving holiday. There was no timetable given on how long it will take to find the cause of the fire.

"Once that determination to the fire is made, and a fire investigation is necessary, then ATF will continue as a partner with the fire department and police department in that investigation," said Porreca.

"This isn't time to say this is ours, this isn't about turf,” said Caufield. “This is about getting the job done properly for the community."

So far, all agencies are following up on leads and interviewing witnesses while they search for the cause of one of the largest fires in recent memory.