A strike by thousands of Long Island Rail Road employees brought the nation’s busiest commuter railroad to a standstill early Saturday, disrupting travel across the New York metropolitan area and setting up a major labor standoff between transit officials and union leaders.

Train service was halted shortly after midnight when five labor unions representing nearly half of the railroad’s workforce launched a walkout after contract negotiations with the Metropolitan Transportation Authority collapsed. It marks the first rail strike on the system in roughly 30 years.

The shutdown immediately affected commuters traveling between New York City and Long Island, with officials warning riders to expect significant delays and overcrowding on alternate transportation options throughout the weekend.

At the center of the dispute are disagreements over wages and rising healthcare costs, the Associated Press reported.

Union leaders argue workers deserve higher pay amid inflation and increased operating demands, while transit officials have pushed for employees to contribute more toward medical coverage as the agency faces mounting financial pressures.