Several Jamaican Olympic track and field running medalists tested positive for banned substances.

Tyson Gay, the fastest man from the 100mm, had an unidentified banned substance in his system. Along with Gay, Asafa Powell, Nesta Carter, and four other Jamaican runners tested positive, according to the Daily Mail. If drug usage is proven, three of the fastest men will have to miss the World Championship in Moscow this August.

According to the Telegraph, Powell and Gay has stayed firm that they are innocent and that they unknowingly took the substance, but will face the consequences if punished.

“My attitude towards doping regulations and testing is well known and I willingly give samples whenever requested. This result has left me completely devastated in many respects,” Powell said in a statement.

This is not the first time there has been a scandal with failed drug testing in running. Last month, Olympic relay medalist, Sherone Simpson tested positive for oxilofrine at the Jamaica’s national trials. Veronica Campbell-Brown, a world 200m champion, was suspended after she tested positive for a banned masking agent.