CHAMPAIGN Investigators spent Sunday going through the interior of a Campustown building that was hit by a fire last week but fire department officials still don't know how long it will take before the cause is determined.

"The investigators are trying to sift through a lot of material," Champaign Fire Department spokeswoman Dena Schumacher said Sunday afternoon. "It's like trying to put together a puzzle."

Capt. Wayne Huckstadt of the Champaign Fire Department said investigators from the department and the state fire marshal's office spent much of Sunday at 625-627-629 E. Green St., C.

Huckstadt said the investigators entered the building at about 7 a.m. Sunday to survey the damage and pursue the cause of a Wednesday morning fire that hit the building housing Zorba's and Mia Za's Cafe restaurants and the Pitaya clothing store.

The investigators took a look at the damage in the building, took photographs of the interior and brought along a dog that has been trained to sniff for possible accelerants.

"They were looking for anything that may lead them to the cause of the fire," Huckstadt said.

Green Street between Sixth and Wright streets re-opened to traffic before 6 p.m. Sunday.

Schumacher said the street had been closed until the area could be made safe for vehicles and pedestrians because of the possible danger of collapse and falling debris from the building following the fire.

The investigators weren't able to enter the building until partial demolition of the property by Dig It of Champaign had been completed.

Schumacher said the demolition involved removing the front wall of the building on Green Street down to the limestone capstone ribbon running across the front of it. In addition, masonry was removed down to the second-floor ceiling on the back side of the building.

Schumacher said the partial demolition of the building was finished Saturday evening.

"Champaign fire investigators began their work once the structural engineer from Frauenhoffer and Associates declared the building safe for sidewalk and street traffic," Schumacher said.

Schumacher said business owners will be able to return to the building once the fire investigation is completed.

Schumacher said the fire department received reports of a fire near Green and Wright streets at 7:57 a.m. Wednesday. Both Champaign and Urbana firefighters responded to the call, using 11 fire engines, four ladder trucks and two squads at the height of the fire, she said.

Firefighters dealt with a partial roof collapse of the 1920s-era building at about 8:30 a.m., she said.

She said the fire was fully extinguished before 10 a.m. Wednesday.