Austria concert shooting
Austrian police are investigating a shooting at a concert that left 11 people injured and three deadHeinz-Peter Bader/Reuters

A gunman has opened fire on a crowd at a concert organised by The Lords motorcycle club in western Austria, killing two, before committing suicide after a "relationship dispute". The 27-year-old assailant injured at least 11 other people and forced up to 150 terrified revellers to take shelter in nearby woodland.

The German-language news website Vorarlberg Online said the unidentified attacker used a "long gun" – most likely a rifle – to fire 30-40 shots before turning the gun on himself. The shocking attack occurred at the outdoor concert in the western town of Nenzing, around four miles (6km) from the border with Liechtenstein at around 3am on 22 May.

Reports from the Austrian town say that the event has been regularly organised by a local motorcycle club known as The Lords for the last decade. The concert was described as a "great barbecue with music" with motorcycle enthusiasts and other people in attendance.

On the website The Lords say they have connections across Europe and described the event as "the biggest biker event in Vorarlberg" including "48 hours of non-stop parties with live music".

Local news reports have stated that the man went berserk following a "relationship dispute" with a woman in a car park. Austrian public service TV station ORF said the man became "enraged" and then shot "wildly into the crowd". He then was said to have returned to the car park where he shot himself.

Vorarlberg Online said that the woman who he had argued with was unharmed in the incident and that police have launched an investigation into whether the firearm was legal or not.

The injured revellers have been taken to various hospitals across the state of Vorarlberg by ambulance. Eight rescue workers, three ambulances and 25 Red Cross staff were on site, and 50 more were on standby.

The injuries were "very different," said police spokeswoman Susanne Dilp said, but did not comment on how severely people were hurt. The Spiegel Online said that a police spokeswoman told them that the "exact course of events is still unclear".

Mayor of the town, Florian Kasseroler, confirmed that the revellers took refuge amongst the trees: "The people have fled in panic into the forest. There are probably like 30 to 40 shots, but I'm not sure."