Explosions that rattled downtown Denver and kicked up smoke early Sunday came from sewer lines blowing off manhole covers, fire department officials said Monday.

The explosions happened shortly before 3 a.m. near the intersection of 18th and Arapahoe streets.

“We had manhole covers bursting. We saw smoke,” Denver Fire Department spokesman J.D. Chism said.

Before dawn Sunday, a Denver Water main line broke in the area and a utility junction box apparently blew up, police and fire officials said. These incidents may have played a role.

Xcel dispatched crews to that area “after Denver Fire reached out regarding an incident in the area that included a utility vault,” utility spokeswoman Michelle Aguayo said late Monday in response to emailed queries.

“There were no injuries related to this event,” and customers in the area did not lose electric service, Aguayo said.

“We are working with the City of Denver and Denver Water to better understand the series of events that led to the manhole cover shooting into the air, and the damage caused to Xcel Energy and Parks and Recreation equipment in the area,” she said.

“We can confirm that Xcel Energy did not have a natural gas leak in the area.”

Several residents downtown reported hearing explosions and seeing gray smoke billowing above buildings near 18th and Arapahoe.

Manhole covers typically explode after a spark from wiring ignites gas. A cast-iron manhole cover can weigh between 85 and 300 pounds and explosions in the past have propelled these discs into the air.

Editor’s note: This article was updated at 12:39 p.m. May 16, 2023, to include Xcel’s response to questions about the incident.

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