Those who know Alameda resident Stephen Michael Petersen were stunned to learn Monday that their friend — a guitar player who fronts a folk band — was one of two men arrested on suspicion of setting a string of fires in the city that damaged or destroyed several homes and businesses.

Petersen, 27, is a well-liked musician who hosts an open mike night in Alameda and keeps a strict vegan diet, according to his friends. But he was nabbed by police at 2:43 a.m. Sunday in front of his apartment amid a rampage of fires that began to break out within a 7-block radius just before 1 a.m., authorities said.

“I’ve known him for five years and consider him a friend,” said 28-year-old Jesse Strickman, a musician who has performed several times with Petersen. “He’s a very nice guy. He is extreme, but I don’t think he would do anything that would hurt anyone.”

Petersen’s brother, Eric Marcrum of San Diego, said police arrested the wrong person.

“It does not sound like anything my brother would be involved in. He’s a pacifist. He abhors violence,” said Marcrum, 40. “I want to see these charges dropped, and I want to see him released.”

The other suspect, 22-year-old Andrew Resto Gutierrez, said to be a transient who frequents Alameda, was arrested at 4:49 a.m. Sunday, police said. A day later, authorities were working to see how the men were connected, said Alameda police Lt. Jill Ottaviano.

No one was injured in the fires that ultimately racked up $3 million in damage and displaced four families, Alameda fire officials said.

The first fire was reported at 12:56 a.m. — a trash bin blaze on the 1300 block of Regent Street that crews quickly extinguished. Soon crews from multiple East Bay agencies were responding to a rash of fires that they would spend hours putting out, said Capt. Jim Colburn of the Alameda Fire Department.

At 1:39 a.m., someone set the back of a two-story home on the 1100 block of Regent ablaze, causing an estimated $100,000 in damage. Then a two-story Victorian duplex on the 2200 block of San Antonio Avenue was set on fire, Colburn said. Four sleeping children escaped from the rear unit, but there was $300,000 in damage.

The most devastating fire was reported just after 4 a.m., after Petersen’s arrest. At least five businesses were damaged when a fire spread from the alley behind a commercial strip on the 1600 block of Park Street, Colburn said.

The fire destroyed Angela’s, a Mediterranean-style restaurant, and Brite 1-Hour Cleaners. Investigators estimated $2.6 million in losses.

'Out of character’

Justin Vanegas, 29, another musician in the Alameda scene, said he is one of Petersen’s closest friends. The two trade off doing sound engineering at Rooster’s Roadhouse on Clement Avenue. On Saturday night, Vanegas said his friend was working at the bar and got off his shift around 1:30 a.m. before walking home.

“This is completely out of character,” Vanegas said. “I think he was in the wrong place at the wrong time. This whole thing just doesn’t add up. I’m really confused. None of this makes any sense at all.”

According to his friends, Petersen graduated from San Francisco State University and is straight edge, a hard-core punk subgenre whose adherents refrain from using drugs or alcohol.

On Aug. 25, Petersen posted a picture on his Facebook page of a Germanic rune on an anarcho-communist flag, which he said shows he is a “pagan but anti-fascist.”

In a line describing himself, Petersen wrote, “I believe in non-violence adamantly, I'd rather let you hit me than try to hurt you, for in the words of Gandhi: 'An eye for an eye makes the whole world blind.’”

'Not a violent person’

Strickman, who fronts the band Dear Indugu, had Petersen sing on his most recent album.

“I opened for him, and he’s opened for me,” he said. “He’s not a violent person. He is very political and really believes in animal rights.”

Vanegas added, “He definitely has the protester in him, but he’s never violent in any way, shape or form.”

Petersen and Gutierrez are being held at Santa Rita Jail in Dublin in lieu of $750,000 and $1 million bail, respectively. They have not been charged but are scheduled to appear Tuesday in Alameda County Superior Court in Oakland.

Evan Sernoffsky is a San Francisco Chronicle staff writer. E-mail: esernoffsky@sfchronicle.com Twitter @EvanSernoffsky