COPENHAGEN, Feb. 14 -- A massive manhunt is underway across Denmark after a gunman killed one man and wounded three police officers on Saturday afternoon at a cultural center in the downtown area of Copenhagen.

Sirens were heard from time to time as police vehicles were still rushing along the streets of the capital late in the night.

"We are on a high alarm all over the country, and our main priority at this stage is to catch the perpetrators and make sure that we find them as soon as possible," Danish Prime Minister Helle Thorning-Schmidt told reporters after the attack.

The shooting occurred around 4:00 p.m. local time (1500 GMT) at the cultural center Krudttoenden, where French Ambassador to Denmark Francois Zimeray and Swedish cartoonist Lars Vilks were participating a meeting under the name of "Art, Blasphemy and Freedom of Expression."

The police said they suspected that the shooting was against Vilks, who has aroused anger in religious circles with a drawing of Prophet Mohammed as a dog.

At a press conference, a Copenhagen police spokesman said that given Vilk's participation, it is very natural to assume that the shooting was a terror attack and it is being investigated as such. The Danish Security and Intelligence Agency (PET) also said the shooting seemed planned.

Thorning-Schmidt told media that the shooting was "a politically motivated attack, and thereby it is terrorist attack."

She said she was deeply angry with the shooting, and the authorities' first priority now is to catch the perpetrators.

"We will do everything to find the guilty parties and bring them before a court," the prime minister said in a statement.

"We have some tough days ahead of us, in which our solidarity will be tested. But in Denmark, we will never yield to violence," she said.

Copenhagen police initially suspected there were two gunmen involved, but later said they believed just one gunman was behind the shooting.

According to a photo and description released by the police, the suspected gunman is a 25-30 year-old with an Arabic appearance.

SORROW MIXED WITH ANGER

The shooting happened at a time when the city was in a cheerful mood on the day of Valentine's Day.

"I am horrified and deeply affected by the shooting at Krudttoenden. My thoughts and prayers are with the victims and their families," Copenhagen city mayor Frank Jensen said on his Twitter post.

An Internet users, under the screen name of Abhijeet Mishra, said on the website of The Copenhagen Post: "Walking on the high embankment along Highway E47 near Lyngby, I was surprised to find so many police cars headed towards the city center at unusually high speed. I now know the answer."

"An unfortunate event. Rest in peace the innocent who was killed in this irresponsible incident," the user wrote in a comment after the report.

While others are expressing their anger and confusion toward the incident.

"Why is it acceptable to have anti-Muslem speech in Denmark? There must be a few closet Neo Nazis lurking about," said another user with the screen name Eduardo Aenlle.

While another user, who is obviously a Muslem with the name of Abdulla Ali, said, "I hope justice is served. Some idiot is gonna make normal, peaceful, hardworking taxpayers like me look bad because of my name and how I look like."

Copenhagen deputy mayor Anna Allerslev wrote on Twitter that a memorial would be held outside of the cultural center on Monday.