SANTA CRUZ — Downtown business owners spent Sunday repairing shattered windows and doors after a May Day rally Saturday night turned into a riot with approximately 250 people marching along Pacific Avenue, some carrying makeshift torches, throwing large rocks and paint bombs, and spray-painting walls with graffiti.

At least 18 businesses suffered damage during the rally in honor of international workers that began at 9 p.m. and escalated into mayhem around 10:30 p.m., police said. Investigators estimated damage at $100,000, though some business owners said it could be more. No injuries were reported.

On Sunday, sea green-colored glass littered sidewalks where windows and glass doors had been smashed. Maintenance workers, many getting called in the middle of the night, boarded up windows with plywood until new sheets of glass could be installed.

The vandalized businesses included Urban Outfitters, Peet’s Coffee, Noah’s Bagels, Jamba Juice, Velvet Underground and Dell Williams Jewelers. The unoccupied Rittenhouse building also was damaged. A police car was vandalized with rocks and paint, department spokesman Zach Friend said.

Roxie Jones, a resident at Palomar Apartments, spent Sunday morning cleaning yellow paint blobs off of her white Pontiac Grand Prix, which was parked on Pacific Avenue during the riot.

Velvet Underground owner Diane Towns said she was sickened by the smashing of a large window at her north Pacific Avenue clothing store, which has been downtown since 1994. Vandals also dragged a mannequin out of the store and tore off the dress and jewelry, she said.

“We’ve been up all night. I’m just devastated,” Towns said Sunday morning. “We’ve had a hard enough time staying open with the economy, now this. It’s going to cost me at least $1,000 to replace the window.”

Kevin Melrose, manager of the Rittenhouse building, estimated it would cost more than $30,000 to replace the three windows and two doors that were smashed in the riot. There was also damage to some artwork being stored inside the vacant building at Pacific Avenue and Church Street, he said.

“This is just stupidity,” Melrose said. “This is a violent protest to me, and it diminishes their cause.”

The only person arrested in connection to the downtown destruction was Jimi Haynes, a 24-year-old transient from Fresno County. Police said Haynes was seen breaking two large display windows at Dell Williams Jewelers, a longtime family-owned local business. He was booked into County Jail on suspicion of felony vandalism and a parole hold.

Police said Haynes told them he learned about the May Day rally from a flier posted at the Santa Cruz anarchist cafe, Sub Rosa, which is at Spruce Street and Pacific Avenue. Several fliers had circulated around town and on the Internet advertising a May Day street party in Santa Cruz.

The fliers didn’t contain names or groups responsible for the event.

“Take back this day. Kick it with us for a truly sick night of mayhem,” a flier said.

Another flier billed the event as a chance to “celebrate, eat, drink, dance and take over,” while another predicted a “massive” street party.

Police said they knew the May Day event was being planned, but felt there was no need to monitor it closely because there was no indication it would turn destructive.

The city event coordinator Kathy Agnone had reached out to the group to encourage them to obtain a permit, but they refused, Friend said.

“There were fliers, but there wasn’t any indication it would be this kind of event,” Friend said. “The fliers we had didn’t give any indication like that.”

Scenes from the downtown riot were caught on video and posted online to YouTube. The short clips show a mass of people marching down Pacific Avenue. Three or four individuals dressed all in black, their faces covered, darted out of the crowd to storefronts, swinging what appeared to be tire irons at windows and in some cases throwing rocks the size of bowling balls.

In some cases, the rocks remained Sunday morning on the sidewalks where they fell.

No police were seen in the video while the destruction was under way. Later, the video showed the street mostly empty as police cars and officers on foot moved through the area.

Friend said there were eight officers on duty in the city, including two downtown, when the 911 call came about 10:30 p.m.

Instead of facing an unruly crowd in which police were outnumbered 20 to 1, Friend said, the officers requested mutual aid from every law enforcement agency in the county, including Watsonville, Capitola, UC Santa Cruz, California Highway Patrol, harbor police and sheriff’s deputies.

“Every available resource responded. Obviously it takes time to get all of the county’s resources assembled,” Friend said. “Once we were there, it was contained in less than 20 minutes and the crowd dispersed and the vandalism stopped.”

Police said they expect to make more arrests. They hope surveillance video taken at various businesses will help them identify those involved.

Councilman Ryan Coonerty, whose family owns a downtown bookstore that was not damaged in the riot, described the vandalism as “childish, asinine, pseudo-revolutionary acts” that take police away from other critical public safety needs such as those connected to gangs.

“The fact is between the gang violence and the acts of violence downtown, we need more police,” Coonerty said Sunday. “We’ve authorized a lot of overtime to deal with the gang problems and that costs a lot of money. We’re going into the red for overtime because we think it’s important to have extra police on duty right now. But going into the red is not sustainable.”

Coonerty said he planned to talk to police today about how city officials can better support the department’s efforts to curtail crime.

Chip, the head of the Downtown Association who goes by only one name, said the business owners he talked to on Sunday were frustrated by Saturday’s “senseless” violence.

“The victims in this are our community, the businesses and families trying to make a go of it,” Chip said. “These are selfish idiots. It doesn’t make sense.”

The owners of Zocolli’s Italian deli on Pacific Avenue received phone calls at home at 1:30 a.m. Sunday alerting them to the uprising. The fact that their business escaped damage didn’t diminish their anger over the vandalism downtown.

“It’s disgusting,” Caitlin Zocolli said. “They’re just making themselves look terrible. It just makes them look like animals. For all they know, we’re all on their side.”

Katy Hope of Newport Beach was shocked to see the destruction while shopping downtown with her daughter Rosie on Sunday.

“This isn’t a protest. This is violence,” Hope said. “This is really wrong.”

Georgeta Cole, a Sacramento resident visiting Santa Cruz for the day with her fiance, said the vandalism was inexcusable.

“It’s irritating that people destroy property to get their point across,” Cole said. “It’s horrible.”