MADISON, Wis. -

Investigators and experts from across the country are looking into a wide range of causes of a fire at a far east side apartment complex Friday night.

The United States’ Department of Justice’s Bureau of Alcohol, Tobacco, Firearms and Explosives has investigators on the scene because of the size of the fire and because it was a commercial property, officials said.

"ATF is investigating this fire with our state and local partners and will work together as one unit to determine the origin and cause of this fire," said ATF acting Special Agent in Charge Jeffery A. Magee, of the St. Paul Field Division.

ATF investigators at the Apollo Way apartment complex said they are not ruling out any causes at this time, and there’s no timeline on the investigation.

"We have a lot of different fire subject matter experts we have brought in from all across the United States, and we have a lot of tools and sophisticated machinery so they can process this scene," ATF Special Agent Joel Lee. "We are going to take our time. We are going to do a very methodical dissecting of this entire scene, so we have a very good understanding of what happened."

ATF officials estimate the total loss of the 105-unit Grandview Commons complex to be between $3.5 and $5 million.

An estimate of damage caused by the fire is still not available, and Madison Fire Department officials are still asking the public to send in their pictures and videos of the fire to aid in the investigation.

The fire was initially reported by drivers on Interstate 90 who saw smoke and flames at about 7:30 p.m., MFD spokeswoman Lori Wirth said.

Firefighters en route to the site saw smoke and flames come from the back side of the building on the third and fourth floors from a half mile away, according to a release.

Heat from the fire caused crews to move back from the building, as heat was melting plastic on the fire engine and breaking window glass.

"Because the building was under construction with no occupants, crews adopted a defensive strategy to protect the occupied dwellings,” Wirth said.

Heat from the fire caused damage to houses nearby, melting siding and cracking windows. Firefighters hosed the buildings with water to cool them and prevent structural damage, according to the release.

Crews had the fire under control by 9:37 p.m., but remained on Apollo Way to maintain control. Pallets of building materials across the estimated 2-acre fire continued to smolder Saturday, fire officials said.

The building is owned by FMI Development. In a statement, Dan Schmidt, a manager at FMI, said the group is thankful no one was injured in the blaze. He said FMI plans to rebuild.

News 3 requested inspection reports from the Apollo Way property. No major issues were found since construction started in February, but developers did reschedule inspections of electrical, heating and cooling work that were set to be done Friday.

The building inspection supervisor said rescheduling inspections isn't out of the ordinary, but he couldn't say why it was rescheduled.

Wirth said fire investigators are interested in photos or videos from the public that were taken of the fire scene before crews arrived Friday. Anyone with relevant media can call 608-266-4420 or email MFD@cityofmadison.com.