The City of Mount Vernon is throwing out the results of June’s promotional exams for fire captains and lieutenants due to cheating allegations.

A letter obtained by News 12 says the city’s Municipal Services Commission revoked the list of eligible firefighters following an investigation into exam security.

The investigation cited the alleged use of electronic reading devices, cellphones and a copy of an exam booklet from another municipality.

All candidates have been disqualified because of the suspected security breach.

The number of people who took the test is unclear. A new set of promotional exams will occur next year.

A city spokesman referred all comments to the firefighter’s union. News 12 is waiting to hear back for comment.