Two dead at Jehovah’s Witnesses center in Colorado

Police in Thornton, Colorado, say they found two adults dead after investigating a suspected murder-suicide at a Jehovah's Witnesses Kingdom Hall on Christmas morning.

Officers in the suburb north of Denver tweeted at 10.30am Sunday that they were investigating a homicide at the gathering place but that "there [was] no active threat".

Thornton police later said the fatalities were a married couple and former members of the Kingdom Hall congregation.

"An adult female was shot and killed by an adult male, who then shot and killed himself," authorities said in a statement. The identities of the couple have not yet been released.

"The investigation is still active, witnesses being interviewed, scene being examined," Thornton police said on Twitter. "Still no known threats to the Thornton community."

In addition to the couple dead at the Kingdom Hall, a hazardous material team was investigating what it described as a "suspicious device" believed to be connected to the murder-suicide, authorities said.

Luis Sanchez, a witness who lives across the street, told the Denver Post that he heard two gunshots Sunday morning. He said he looked outside to see a woman lying on the ground outside.

"It's very sad," he said. "It's Christmas."

According to a Fox News report, the attacker threw a type of explosive known as a molotov cocktail into the building. Reports of further explosions followed.

Fire services had also reportedly headed to the scene in response to reports of a blaze at the building.

Authorities have said little about those details beyond noting the presence of the hazardous materials team at the Kingdom Hall.

Police have not released information about the suspected killer. They asked the public to avoid the area.

In the UK, Samaritans can be contacted on 116 123 and the domestic abuse helpline is 0808 2000 247. In Australia, the crisis support service Lifeline is on 13 11 14 and the national family violence counselling service is on 1800 737 732. In the US, the suicide prevention lifeline is 1-800-273-8255 and the domestic violence hotline is 1-800-799-SAFE (7233). Other international helplines can be found via www.befrienders.org