OSLO, June 25 — A gunman went on a terrifying rampage in a gay bar and surrounding streets in Oslo on Saturday, killing two people and seriously injuring 10 on the day the city’s LGBTQ community was due to celebrate its annual Pride parade.

The victims were shot inside and outside the London Pub, a well-known gay bar and nightclub open since 1979, as well as at one other bar in the centre of the Norwegian capital.

"I saw a man arrive with a bag, he picked up a gun and started to shoot,” said journalist Olav Roenneberg of public broadcaster NRK, who was in the area. "Then I saw the windows breaking and understood that I had to take cover.”

A suspect, a 42-year-old Norwegian citizen of Iranian origin, was detained minutes after, according to police who said they believed he acted alone. Two weapons, including a fully automatic gun, were retrieved from the crime scene, they added.

"There is reason to think that this may be a hate crime,” officers told a news conference. "We are investigating whether the Pride was a target in itself or whether there are other motives.”

Oslo police spokesman Rune Hekkelstrand told Reuters the attack was also being investigated as a possible act of terrorism.

Norwegian Prime Minister Jonas Gahr Stoere decried the shootings as a "terrible and deeply shocking attack on innocent people”.

The suspect was known to authorities, including for violence of a less severe nature, police said.

The shooting happened in the early hours of Saturday, and just months after Norway marked 50 years since the abolition of a law that criminalised gay sex. Eleven people also suffered minor injuries, police said.

Organisers of Oslo Pride cancelled Saturday’s parade, citing police advice. "We will soon be proud and visible again, but today we will mark Pride celebrations at home,” they said.

Norway, a country of 5.4 million, has lower crime rates than many other Western nations, though it has experienced hate-motivated shootings, including when far-right extremist Anders Behring Breivik killed 77 people in 2011. — Reuters