Norway raised their terror alert level after a man killed two people outside a popular LGBTQ nightclub in the capital Oslo on Saturday, DW reports.

Police said that the alleged shooter was known to the police since 2015 as a suspected radical Islamist. The authorities are treating the incident as an "act of Islamist terrorism," the officials said.

The suspect "has a long history of violence and threats" as well as mental illness, authorities said. Acting chief of Norway's domestic intelligence service PST, Roger Berg, said the alleged shooter has been on the agency's radar on suspicion of membership "in an Islamist extremist network."

Previously, police confirmed two people were killed and more than a dozen injured in the shooting, which came just hours before Oslo's annual Pride parade.