An explosion in Westminster, Colorado on Thursday left two people injured and destroyed several houses. Westminster is a suburb located just north of Denver.

According to the Westminster Fire Department, the explosion occurred at around 11:30 am. The surrounding block was evacuated due to concerns that another explosion could follow.

According to the Denver Post, the explosion is thought to have been caused by natural gas. Local residents reported smelling gas shortly before the explosion. Energy company investigators are now determining whether a gas leak could have caused the incident.

One home was completely destroyed, reduced to rubble. The owners of that house were away at the time, and are fine. Another house was severly damaged, and two others suffered relatively minor damage.

Two people were injured as a result of the explosion. However, the Post report states that both of the injuries were suffered by rescue workers: a police officer, who stepped on broken glass, and an energy company worker whose injury was not disclosed.