A sanitation worker was injured after an explosion in a sanitation truck on Thursday, and the Department of Sanitation believes that a helium tank was the cause.

The incident occurred at 6:40 a.m., near 7th Avenue and 12th Street in Park Slope Brooklyn. Officials suspect a helium tank exploded in the hopper of a truck, which then knocked over a sanitation worker. The Fire Department also responded to the incident.

The hopper is where the trash is collected and then compacted.

The worker was taken to a local hospital. The Department of Sanitation said he did not appear to have a life-threatening injury; WCBS 2 reports that he suffered cuts to his chin.

It is illegal to throw helium tanks away in the trash in NYC. The Department of Sanitation recommends that they be recycled, after the valve is removed.