Police said a person was arrested at the scene of the attack at an event after the Hard Summer techno festival at Hollywood Park

A shooting erupted during a music festival after-party in downtown Los Angeles, killing two people and wounding six others early on Monday, authorities said.

Police first responded at around 11pm on Sunday to shut down a “big party” after officers saw a person possibly armed with a gun go inside a building in a downtown warehouse district, said police officer Norma Eisenman. That person was arrested at the scene, she said.

The party had been promoted on social media as an unofficial after-party for Hard Summer, a weekend techno music festival held at Hollywood Park, about 14km (9 miles) away in Inglewood, KTLA-TV reported.

Soon after officers had cleared the area, police received a report of shots fired at around 1am. When the officers returned, they found one person dead and learned multiple people had been struck by gunfire, Eisenman said in an email.