OSLO, Norway — Two people were killed and at least 19 injured early Saturday morning in downtown Oslo when a gunman opened fire outside two nightclubs and a diner, the police and Norway’s state broadcaster said.

A male suspect was apprehended five minutes after the shooting was reported, the Oslo police said on Twitter. Tore Barstad, a police operations chief who spoke to reporters about the incident, did not identify the suspect or speculate about a motive. He said three of the wounded were seriously injured.

One of the two nightclubs, the London Pub, is a center of gay nightlife in Oslo. The city’s annual Pride parade, a highlight of a ten-day festival that began last week, was scheduled to take place Saturday.

Olav Rønneberg, a crime reporter for the Norwegian public broadcaster, NRK, happened to be in the area when the violence began. “I saw a man arrive at the scene with a bag, he took up a gun and started shooting,” he told the outlet.

The London Pub, which lies a few blocks from Norway’s Parliament building, opened in the 1970s. A picture of the bar in a listing on Oslo’s official tourism website shows a rainbow flag hoisted above its entrance.

The timing and the location of the attack raised concern that it may have been intended to target the L.G.B.T.Q. community in Norway, where gay couples have had the right to marry and have children since 2009.

Shootings are exceedingly rare in Norway, a country of five million people whose capital lies beside a picturesque fjord.

Gun owners must be licensed and take safety classes, and a ban on semiautomatic weapons enacted by the Norwegian Parliament — a response to a 2011 attack by a far-right gunman that killed 77 people — took effect last year.

The 2011 attack started when the gunman, Anders Behring Breivik, detonated a fertilizer bomb in downtown Oslo, killing eight people. He then killed 69 people, mostly teenagers, in a shooting rampage at a political summer camp.

Mr. Breivik received a 21-year sentence for the attacks, the maximum under Norwegian law. He was denied parole in February by a Norwegian court that said he “appeared devoid of empathy and compassion for the victims of the terror.”

Henrik Pryser Libell reported from Oslo and Mike Ives from Seoul.