Three teenagers were arrested Wednesday night in connection with the fourth violent attack on Key West streets in the past three weeks.

In an assault similar -- but apparently unrelated -- to three other recent attacks, 41-year-old Peter Cohens was mugged by three youths as he was walking on Duval Street around 3 a.m. Wednesday, according to a police report. Cohens told officers the youths attacked him from behind, hitting him in the back of the head.

Cohens fell to the ground and the youths kicked him in the ribs while demanding money, police said. His ribs were bruised, but the attackers reportedly did not get any money.

Cohens identified three suspects in a photo lineup, and the three teens admitted involvement in the assault, said Key West Police Department spokeswoman Alyson Crean.

Otha Matthews, 16, Thomas Sipos, 15, and Martin Jonis, 16, were arrested on felony charges of attempted robbery. All are in the custody of the Department of Juvenile Justice.

Police still are looking for two youths involved in a July 8 assault on a visitor staying at a Fleming Street guesthouse.

And in two separate assaults on July 13, two residents were attacked while walking in an Old Town neighborhood near the city cemetery. About 9 p.m., 65-year-old Don Sullivan was assaulted and robbed by four youths in the 600 block of Elizabeth Street, near his home. Minutes later, the same four youths allegedly attacked activist and City Commission candidate Tom Milone, 63, at the intersection of Frances and Angela streets. Milone's injuries, including a broken jaw, were serious enough to require an airlift to Miami.

Four teenagers were arrested a day later in connection with those attacks. Christopher Harris, 17, Cornelius Jones, 17, Thomas Reza, 16, and Jonathan Bein-Aine, 18, were charged with felony counts of aggravated assault and robbery.

While the attacks have been similar, there's no one factor indicating they all are related, Crean said. They appear to be random acts of violence, she said.

"It's not an organized gang issue," she said. "None of the kids are from any one neighborhood. It's hard to speculate."

Key West Police Chief Donie Lee is taking a hard line on the assaults.

"I'm concerned about the growing number of recent attacks," he said Thursday. "But one thing is clear, we will not tolerate this sort of violence in our community."

Last week, Lee addressed the assaults during a Citizens Police Academy seminar, in which he called on businesses and residents for help, saying it's a "community issue," not just a police issue.

"I can't solve the problem alone," Lee told the group.

alinhardt@keysnews.com