Jamaican air traffic controllers have gone on strike, halting flights at the island’s two main airports as of 10 a.m. Thursday. According to the Jamaica Star, transport to and from Norman Manley International Airport in Kingston and Sangster International Airport in Montego Bay is impacted.

Workers have been in a three-month-old disagreement with the Ministry of Finance over salary negotiations, according to the article.

According to the Jamaican newspaper The Gleaner, up to 28 flights to Montego Bay have already been cancelled, with one American Airlines flight from New York’s John F. Kennedy Airport being diverted to Miami and a flight from Charlotte, North Carolina being diverted to Miami, while a flight from Charlotte, North Carolina turned back. Additionally, an Air Canada flight, which was en-route to the island, was also forced to return to Toronto.

Several aircraft were able to land this morning before the workers walked out, including Frontier from Atlanta, Sun Wing from Toronto, and JetBlue from New York.

The air traffic controllers’ return date is unknown, according to the Gleaner. As a result, Howard Greaves, director, air traffic management at JCAA, suspended all services at both airports, including departures.