Townsend said initial indications show there were multiple airstrikes in the area where the buildings are located.
"Is it possible that we did that? Yes, I think it’s a possible," Townsend said later. "That's what I mean by a fair chance. If we didn’t strike in that area, I’d be telling you it was unlikely. But because we struck in that area, I think there’s a fair chance that we did it."
An Air Force brigadier general is leading the coalition's credibility assessment into the claims of civilian casualties at the location in western Mosul where local reports say as many as 200 civilians were killed in demolished structures.
A team of American experts visited the site in Mosul on Monday, gathering samples and information that Townsend said will help determine if a coalition airstrike played a role in the collapse of the buildings.
Cautioning that initial assessments can sometimes be wrong, Townsend said, "My initial assessment is that we probably had a role in these casualties."
"What I don’t know is were they gathered there by the enemy?" Townsend asked. "We still have some assessment to do. It sure looks like they were. I firmly believe they were gathered there by the enemy. The people we're talking to say they were gathered there."
Townsend said that the building had been used by ISIS as a fighting position and that "there were people that you really can’t account for in any other way, for why they would all be there, unless they were forced there."
"My initial impression is the enemy had a hand in this and there's also a fair chance our strike had some role in it," said Townsend. "I think it’s probably going to play out it was some combination. But you know what? I really can’t say for sure and we really have to let the investigation play out."
Townsend pointed out that the buildings in question were completely leveled, but he noted that the types of bombs used in the airstrikes in the general area would not have leveled the building.
"The building should not have collapsed and that's something we have to figure out," he said.
The general also told reporters that allegations of civilian deaths from an airstrike on a Syrian school building are "not credible."
Though the coalition review of the allegations is still underway, Townsend said initial indications are from "multiple corroborating streams" of information seem to indicate that only ISIS fighters were killed in the airstrike.
And ISIS is forcing residents unable to flee the fighting to be human shields. According to Townsend, two houses in Mosul were recently found rigged with explosives while 45 civilian hostages were in one house and 25 in another. The explosives were successfully defused and the hostages were released safely.
Townsend stressed that the coalition takes great care to prevent civilian casualties, though they are sometimes accidental, whereas ISIS targets civilians indiscriminately.
"ISIS is slaughtering Iraqis and Syrians on a daily basis," Townsend said. "ISIS is cutting off heads. ISIS is shooting people, throwing people from buildings, burning them alive in cages and they’re making the video record to prove it. This has got to stop. This evil has got to be stamped out."
"In my mind, all of the responsibility for any civilian deaths, the moral responsibility for civilian deaths in Iraq and Syria belongs to ISIS."