Two of the ambulance workers pelted by coins and projectiles thrown by Tottenham Hotspur fans at Arsenal on Saturday are Spurs fans, it has emerged.

Theo Walcott, who will be out for six months and will now miss the World Cup after damaging an anterior cruciate ligament, was singled out by a section of the away support as he was taken off on a stretcher after injuring knee ligaments in the FA Cup victory at the Emirates Stadium and responded by making a gesture to signal the 2-0 scoreline. In response, fans threw missiles without realising that two of the stretcher-bearers, Daniel Ahmed and Anthony Archer, are Spurs fans.

The Football Association confirmed it will not take any action against Walcott as his gesture was not offensive. His team-mate, Jack Wilshere, was banned for two matches last month after he reacted to verbal abuse from a section of Manchester City fans by making an offensive hand gesture at them.

However, the FA reminded Walcott of his responsibilities and said that it will investigate the conduct of both sets of supporters.

A post on Facebook from Archer suggested that Ahmed had suffered a concussion after being hit by a coin as he helped carry Walcott off, although it was not clear whether that was a serious or a light-hearted comment.

Archer and Ahmed work for the London Ambulance Service but were hired by Arsenal for the match. Photos were posted of them on Facebook helping off Walcott and the pair joked with friends about the incident on the social networking site. Neither Ahmed nor Archer were available for comment.

Ahmed appeared to take the incident in good humour, posting under one photo: "Little does he [Walcott] know he has a Leeds fan and TWO spurs fans protecting him. We truly are professionals." When asked by a friend why neither of them were smiling in the photo, Ahmed replied: "We were being Pelted by coins!!! It hurts!!" Archer later posted under the photo: "Can't believe our own fans!! Dan gets concussion and I end up with a dodgy knee! Cheers Theo!"

An FA statement said: "The FA has contacted Arsenal and Tottenham to seek their observations in relation to objects being thrown from both a home and away section of the crowd at different times during Saturday's FA Cup tie. The FA condemns any such acts and will liaise with both clubs and the Metropolitan Police to identify those responsible and support the strongest sanctions available, including life bans.

"Meanwhile, in relation to the same fixture, The FA has contacted Arsenal's Theo Walcott and reminded him of his responsibilities regarding a 'scoreline' gesture he made in front of away supporters during the game.

"The FA will not be taking any further disciplinary action."