At least 20 people have been arrested following a major fight between two rival motorbike gangs at a hotel in Rotterdam.

Eyewitnesses said shots were fired when the gangs – members of the Hells Angels and the Mogols – started attacking each other and pelting each other with furniture. One person was seriously hurt in the melee but no members of the general public, according to news reports.

The fight broke out at the Van der Valk hotel in the port city and took place both inside and outside the building on the Energieweg. According to the AD, the two gangs had agreed to meet at the hotel, but it is unclear why.

Some of the guests hid in the hotel’s gym while the fight was underway. All were later able to return to their rooms for the night.

‘I heard lots of shots and I thought, this is a terrorist attack,’ Patrick, from Kerkrade, told the AD. ‘I ran way out into the park.’