Officials said nine people suffered minor burns during an accident at an Independence Day holiday fireworks show in Colorado on Friday night.

Virginia Egger, the town manager in Avon, said a malfunction caused a fireworks shell to explode in its tube rather than firing into the sky. She said the misfired shell caused a rack of shells to tip, causing two or three to go off towards the crowd.

The accident occurred about 17 minutes into the 23-minute fireworks show over Nottingham Lake, bringing the event to a halt. The annual event attracts about 20,000 people.

One audience member, Jane Imber, told NBC News that there wasn’t a lot of room in between groups of people, so people could not get up and run.

The cause of the malfunction was under investigation.

Source: Fireworks accident injures nine at Colorado Independence Day show | US news | The Guardian