COPENHAGEN, Denmark (CBSNEWS)-- At least one gunman opened fire Saturday on a Copenhagen cafe, killing one man in what authorities called a likely terror attack during a free speech event organized by an artist who had caricatured the Prophet Muhammad.
The shooting, which also wounded three police officers, came a month after extremists killed 12 people at a satirical newspaper in Paris that had also sparked Muslim outrage with its depictions of Muhammad.
Swedish artist Lars Vilks, who has been repeatedly threatened after depicting Muhammad as a dog in 2007, organized and attended Saturday's event but was not hit by gunfire, police said.
"I saw a masked man running past," said Helle Merete Brix, one of the event's organizers. "I clearly consider this as an attack on Lars Vilks."
She and Vilks were quickly ushered away by the security detail that accompanies the artist whenever he is in Denmark.
There was no immediate claim of responsibility for the shooting, which took place shortly before 4 p.m. (10 a.m. EST). Denmark's security service, PET, said the circumstances surrounding the shooting "indicate that we are talking about a terror attack."
"We feel certain now that it is a politically motivated attack, and thereby it is a terrorist attack," Danish Prime Minister Helle Thorning-Schmidt told reporters. "We take this situation extremely seriously. We are at a high alarm all over the country."
Visiting the scene of the shooting, Thorning-Schmidt said "our highest priority is to get the perpetrator arrested."
Danish police said the gunman used an automatic weapon to shoot through the windows of the Krudttoenden cafe, which TV footage showed were riddled with bullet holes. The gunman then fled in a carjacked Volkswagen Polo that was found later a few miles away, police said.
"I heard someone firing with an automatic weapons and someone shouting. Police returned the fire and I hid behind the bar. I felt surreal, like in a movie," Niels Ivar Larsen, one of the speakers at the event, told the TV2 channel.
Police initially said there were two gunmen but later said they believed there was only one shooter, and described him as 25-30 years old with an athletic build, and carrying a black automatic weapon. They released a blurred photograph of the suspect wearing dark clothes and a scarf covering part of his face.