One day after a fire produced thick clouds of smoke covering downtown, Jefferson’s restaurant remained taped off while the rest of the 700 block of Massachusetts Street had mostly returned to normal.

Investigators from Lawrence-Douglas County Fire Medical worked at the rear of the building Friday to determine the cause of the fire and to evaluate the building’s safety. Officials said Thursday that a cause or damage estimate would not be determined for a couple of weeks.

“It’s bad enough where the fire department can’t determine the extent of the damage,” said Brandon Graham, the owner of the restaurant. “They can’t get in there safely. The roof has too much damage in the back.”

Graham reiterated Friday that the building is “not a total loss,” but the back half of the roof is in “bad shape.”

Jefferson’s has occupied 743 Massachusetts St. for 14 years, Graham said. The building, he said, is about 140 years old.

Nobody was injured in the fire, which began around 11 a.m. on top of the building, before the restaurant opened.

Next door to Jefferson’s, Baan Thai Restaurant suffered “light smoke damage” and will reopen Saturday, according to Brad Blankenship, a general manager for Servpro of West Topeka, which specializes in fire and water damage restoration.

Noodles & Company, which sits on the corner of Massachusetts and Eighth streets, on the opposite side of Jefferson’s, was open Friday.

“The fire department did a great job of minimizing loss to other structures,” Blankenship said. He had 14 employees working clean-up at Baan Thai Friday.

Thursday’s fire also involved a brief power outage in the area, but Westar Energy spokeswoman Gina Penzig confirmed that power had been fully restored to the area, save for Jefferson’s. She said power there cannot be turned on until investigators deem it safe to do so.

Thursday, Penzig said a fuse leading to a transformer about 10 feet behind the building blew around 11 a.m.

Stoplights in the area were also operating Friday, after being disrupted Thursday.