An explosion at an Aurora, Colorado, apartment building Saturday forced hundreds of people to flee their homes and left three people injured, according to authorities.
The explosion occurred at the building on East Alameda Ave. on Saturday morning, when the Aurora Fire Rescue arrived after reports of smoke coming from the building, the fire department said on Twitter. Upon arrival, the crew "began searching for hazards when an explosion occurred," the department said in the Twitter post.
The three people who suffered minor injuries were transported to a local hospital and are expected to recover, NBC affiliate KUSA of Denver reported.
On Saturday afternoon, the fire department still did not know the cause of the explosion, according to a Twitter post.
Between 300 and 400 residents of the building - which is known as Parkside Collective and managed by Holland Residential - were evacuated and in the process of being relocated to a shelter with the help of the Red Cross, a post from the fire department said on Saturday afternoon, adding that "long term accommodations will be coordinated through @RedCross based on need."
The Aurora Fire Department and Holland Residential did not immediately respond to inquiries from NBC News.
Photos the fire department posted to Twitter on Saturday show the building with a gaping hole and debris scattered on the pavement below.
Many residents were unable to retrieve their belongings, and as of Sunday, it remained unclear when any residents would be able to return to the building, Sentinel Colorado reported.
Residents of the building told KUSA that they heard odd noises prior to the explosion, and then saw white smoke and felt the ground shaking at the time it occurred.
"The ground started to shake below the apartment building - at that point we decided to make our way outside," resident Samuel Levy told KUSA. "We walked outside, we noticed some steam coming out of the concrete coming in through the separation in the concrete."
At the time of the explosion, "all the debris just fell off," resident Joe Bham told KUSA. "It was just crazy."
This article was originally published on NBCNews.com