The floor in front of the stage area caved in, creating a seven-by-seven-metre hole during Friday night's Christian rock concert at Central Heights Church in Abbotsford, B.C. The floor in front of the stage area caved in, creating a seven-by-seven-metre hole during Friday night's Christian rock concert at Central Heights Church in Abbotsford, B.C. (CBC)

Two people remained in hospital Sunday after a floor collapsed during a Christian rock concert at an Abbotsford, B.C., church on Friday night. City engineers believe a floor joist may have given way, causing the floor to collapse.

Police said a 41-year-old woman remains on a ventilator at Vancouver General Hospital, while a young person is staying at B.C. Children's Hospital.

Marisa Nichini, a spokeswoman for the Children's Hospital, said the young person being treated there is in "fair condition."

"That means [the patient's] vital sign is stable and within normal limits. The patient is conscious — maybe uncomfortable," Nichini told CBC News Sunday.

The woman is in stable condition, officials said.

Abbotsford police spokesman Const. Casey Vinet said most of the people who fell into the basement some five metres below were youths. Abbotsford police spokesman Const. Casey Vinet said most of the people who fell into the basement some five metres below were youths. (CBC)

About 40 people were taken to four hospitals after a hole opened in front of the stage area during a concert at Central Heights Church, located at 1661 McCallum Road, on Friday night.

City engineers believe a floor joist may have given way, causing the floor to collapse, said Chris Douglas, the church's pastor.

"What they think happened is that one of those joists finally just broke and when the one went, others started to go and it just went, 'Boom, boom, boom, boom!'" Douglas told CBC News Saturday.

Matt Foxall, a structural engineer with Engineered Building Inspections in Vancouver, said floors such as the one in the Abbotsford church aren't designed for people putting pressure on one area.

Pastor Chris Douglas said the church has had more people attending concerts at other times without a problem. Pastor Chris Douglas said the church has had more people attending concerts at other times without a problem. (CBC)

"They're designed for a maximum live load, which is your people load, which goes into the building," Foxall said. "In some cases where you have a crowded hall or building, you can quite easily get over that design load."

About 1,200 people packed the sold-out concert at the church Friday night. Around 9 p.m, the floor in front of the stage area caved in, creating a seven-by-seven-metre hole and sending a large number of people tumbling to the concrete basement about five metres below.

"We were dancing in the front of the stage," Kyle Weber, a teenager who was at the Christian rock concert, told CBC News Friday. "The floor just collapsed. All the speakers just fell down [and] crashed [on to] a lot of people … A lot of people fell through the floor."

Abbotsford police spokesman Const. Casey Vinet said most of the people who fell into the basement were youths, and at least three people sustained serious injuries.

Hundreds pray for the injured

Douglas said greater numbers of fans have attended concerts at the church in the past without a problem.

On Sunday morning, more than 1,000 people gathered at Columbia Bible College in Abbotsford to pray for those injured at the concert.

"It's important to meet today because the explosion has affected us all," said Lori Larsen. "It's good to refocus and remember the things to be thankful for ... Thank God that life was spared."