The city of Buffalo is expecting thousands of out-of-town firefighters from across the country and the world to attend funeral services for fallen Buffalo firefighter Jason Arno later this week. Arno died after a fatal fire on Main Street last Wednesday.

Buffalo Mayor Brown expects more than 1,000 firefighters to attend Arno's funeral service at St. Joseph Cathedral in Buffalo at 10 a.m. on Friday. 

The New York State Thruway Authority announced Wednesday that the exit 7 (Church Street) ramp from I-190 north will be closed from 9:30 a.m. until about 1 p.m. due to the funeral procession on Friday.

Also the New York State Department of Transportation announced that the Buffalo Skyway will be closed from the I-190 to Church Street for a portion of the day Friday.

Members of the public will not be allowed inside, but are asked to line the streets along the funeral procession in support of the fallen firefighter. 

His cause of death is still being determined.

Buffalo Mayor Byron Brown, along with Fire Commissioner William Renaldo and investigators with the Bureau of Alcohol, Tobacco, Firearms and Explosives, provided an update Tuesday on the investigation of the massive fire.

The Main Street building held DC Theatricks, a professional theatrical costume rental company for stage plays and musicals. 

They say the cause and origin are still under investigation, and that it is a slow and methodical process because safety concerns in the building had to be shored up.

Officials say it's too soon to say whether a contractor working on the building had anything to do with it, or if they had the necessary permits.

Investigators are excavating the basement and first floor, and have interviewed more than a hundred people and taken materials from the scene. 

ATF officials say they're using a computer model to determine the progression of the fire and they say they will bring in heavy equipment to do some more digging on Wednesday. They expect the continue working into next week.

"As you know, that's a costume shop that primarily encompassed the space, and they utilized all sorts of equipment such as iron presses, heat cutters things like that to cut fabric,” Walter Shaw, branch chief of the U.S. Department of Justice Bureau of Alcohol, Tobacco, Firearms and Explosives, said. “We look at all these things to see if they might have contributed to the fire cause accidentally."

Renaldo says an evacuation order was given to get out of the building a little more than a minute before Arno used his mayday button to indicate he was in trouble.