Metro on Wednesday said actions by the labor union representing employees led to some service disruptions during the busy July 4 holiday.

Customers may have experienced some delays on Metrobus routes as portions of the workforce arrived to work late. Metro referred to the effort as an “unauthorized labor action.”

“Management is doing everything possible to continue to minimize delays to customers, as well as to ensure compliance with WMATA’s collective bargaining agreement, including seeking legal remedies through the courts,” Metro said in a statement.

The news station Fox 5, citing Metro, said 25 percent of bus operators, 16 percent of train operators, 25 percent of station managers, and 30 percent of rail car mechanics came in late Wednesday morning.

The reports of protests appear to stem from the Amalgamated Transit Union Local 689.

The union issued a series of statements on Twitter. In full, they read:

“The front-line workers of WMATA are fed up with the mistreatment and disrespect they continue to experience from the General Manager Paul Wiedefeld and Metro’s management. Employees are being required to work overtime while being treated like disregarded workers as if Wiedefeld himself is moving thousands on one of Metro’s busiest days. He is not transporting anyone, the front line workers he continues to disrespect are! The general manager could resolve the unrest among Metro’s workforce if leadership stopped holding its workforce in contempt and bargaining with our members through their union in good faith. We hope that Wiedefeld and his leadership team will do so. #WMATA should stop giving inaccurate and fact-less information to the public in an attempt to smear the reputation of Local 689 leaders and members. It is clear that #WMATA leadership is trying to depict the union with an unfounded, negative image to forward their agenda to undermine our union. We at ATU Local 689 have always cared about our customers and take pride in providing them with safe, affordable, and reliable service. We are committed to providing excellent service and believe leadership should be working with us and not against us.”