Frightened commuters took cover on a packed commuter tube after hearing gunshots they initially mistook for a possible terror attack.
Travellers were pictured crouched down on the floor of one of the carriages as they posted pictures on social media showing the drama they had been caught up in.
The underground train was evacuated as it reached El Carmen tube station on Madrid’s Line 5 near the famous Las Ventas bullring, around 2.30pm on Thursday.
Commuters panicked after hearing what turned out to be a starting pistol on a Madrid’s Line 5 near the famous Las Ventas bullring near 2.30pm on Thursday
Police later confirmed they had arrested two men but ruled out any suggestion they were terrorists, with sources linking the incident to an altercation between two drunken South Americans in which one of the men fired a starting pistol.
Frightened local David Rivas, saying he was trapped in an underground train near El Carmen tube stop, wrote on Twitter: ‘We are trapped near Carmen tube stop. The driver says shots have been fired. Can anyone tell us what is going on? Police are in the tunnel.’
He later added: ‘The train is starting up again. We’re reaching Carmen tube stop and are being ordered off the train. Leaving the train now. Witnesses say there’s been a shot fired in the last carriage.’
Services in the area were halted on line 5 as well as on line 2, between the stations of La Elipa and Banco de España near the scene of the drama.
A spokesman for Metro de Madrid, which runs the tube service confirmed around 2.30pm: ‘Tubes suspended on parts of Lines 2 and 5 due to circumstances beyond our control.’
He later added: ‘The police have arrested two men and the situation is under control.’
Services were back to normal around 3.15pm local time.
Spain is on high terror alert following last month’s terror attacks in Barcelona and the nearby seaside resort of Cambrils.
Moroccan-born Younes Abouqaaqoub killed 14 people including British-born Julian Cadman, seven, and injured more than 100 others after driving his van along Barcelona’s famous Las Ramblas boulevard on August 17.
He stabbed another man to death during his getaway.
Hours after the Ramblas attack, five other members of the gang ploughed into pedestrians in Cambrils before going on the rampage with an axe and large knives and stabbing one person to death.
The five were shot dead by police.