(CNN) A man suspected of burning a synagogue in Duluth, Minnesota, said he tried to put out the fire by spitting on it and walked away when he was not successful, according to a criminal complaint.

Matthew Amiot faces one count of negligent fires and one count of negligent fires with an injury to a person, according to the police probable cause statement obtained by CNN affiliate WCCO

A court hearing was held Monday and bond set at $20,000.

An attorney representing Amiot said the man denies all allegations against him, according to Duluth affiliate KBJR , but court documents say he admitted to setting combustible materials on fire outside the building.

Police over the weekend said they do not believe the burning of the nearly 120-year-old synagogue was a hate crime. Investigators have no indication that the fire was motivated by hate or bias, Duluth Police Chief Mike Tusken said.

He did not provide an alternative motive but said the investigation is ongoing.

"This may change as the investigation progresses," Tusken said. "But at this date and time, that is the determination that we have, that I have."

The Adas Israel synagogue caught fire last Monday, authorities said. Amiot used a lighter to set fire to a sukkah, a separate structure, police said. The fire quickly spread to the main building nearby.

Debris from the collapse of the building struck a firefighter, who was knocked unconscious and hospitalized for a concussion.

The synagogue could not be saved and was deemed a total loss, according to court documents.

The Bureau of Alcohol, Tobacco, Firearms and Explosives was called in to assist with the investigation, Duluth Fire Chief Shawn Krizaj said -- a standard move for fires involving places of worship.

Authorities determined the point of the fire's origin was outside the building, Krizaj said. There was no indication that an accelerant was used, he said. "That's usually an indication of people's intent. If they want to start a fire, accelerants are usually a common theme that we would find."

It's unclear whether Amiot is represented by an attorney.

'We're not out for vengeance,' rabbi says

Amiot, 36, was arrested Friday, interviewed and booked in the St. Louis County jail for first-degree arson, Tusken said.

Police have had "multiple contacts" and "there have been some arrests," Tusken said, but nothing as significant as an alleged arson.

Matthew James Amiot, 36, is accused of starting the fire.

Amiot was "completely unknown" to the congregation, Rabbi Phillip Sher told reporters.

"I will not speculate as to the man's motives," Sher said. "And as a matter of fact, I would warn everybody that you're innocent until proven guilty, and that's America as it should be."

"We're not out for vengeance," he added. "All I can find out of this event is sadness for everyone."

Sher praised the efforts of firefighters and police, calling their actions "heroic." Firefighters went back into the building, which was still on fire, Sher said, to save religious artifacts important to the congregation.