At least five people have been killed and 25 injured after a gunman opened fire inside a gay club in the US state of Colorado on Saturday night. A suspect is in police custody and is being treated for injuries. Two “heroic” people in the club subdued the attacker, police say.

Club Q, in Colorado Springs, wrote on Facebook that it was “devastated by the senseless attack” on its community.

US President Joe Biden said Americans “cannot and must not tolerate hate”.

Police asked people to be patient while they worked to identify victims and finalise the number of casualties, adding that some people had taken themselves to hospital. Officers received an initial emergency call about an active shooter at 23:57 local time on Saturday, they said.

The suspect was found inside the club. Two firearms were found at the scene, and the attacker is thought to have used a long rifle. Police did not suggest a motive for the shooting but said the investigation would consider whether it was a hate crime, and if more than one person was involved.

A fire department spokesman said casualties had been transported to hospitals very quickly because of training for such events. The FBI in nearby Denver said it was assisting local police with the incident.

Police chief Adrian Vasquez thanked the two club-goers who intervened to stop the shooter. “Initial evidence and interviews indicate that the suspect entered Club Q and immediately began shooting at people inside as he moved further into the club,” he told a news conference on Sunday. “While the suspect was inside of the club, at least two heroic people inside the club confronted and fought with the suspect and were able to stop the suspect from continuing to kill and harm others. We owe them a great debt of thanks.”

A statement on the Club Q Facebook page thanked “the quick reactions of heroic customers that subdued the gunman and ended this hate attack”. The club was hosting a dance party at the time, and had planned to hold a performance event on Sunday evening to celebrate Transgender Day of Remembrance.

Colorado Springs mayor John Suthers called the event a tragedy. “We are a strong community that has shown resilience in the face of hate and violence in the past, and we will do that again,” he said.

The suspect in custody was named as Anderson Lee Aldrich, 22.

The state of Colorado has seen other mass shootings, including at a supermarket in Boulder in 2021 in which ten people were killed. Governor of Colorado Jared Polis, who is gay, praised the “brave individuals who blocked the gunman, likely saving lives in the process”.

“Colorado stands with our LGTBQ Community and everyone impacted by this tragedy as we mourn,” he wrote in a Facebook post.

In a statement from the White House, President Biden said: “Places that are supposed to be safe spaces of acceptance and celebration should never be turned into places of terror and violence. Yet it happens far too often. We must drive out the inequities that contribute to violence against LGBTQI+ people.”

In 2016, 49 people were killed and more than 50 injured in a shooting at the Pulse gay club in Orlando, Florida. At the time it was the deadliest mass shooting in US history.