WASHINGTON — The international prostitution scandal at the Secret Service claimed its first casualties Wednesday, with the agency announcing that three agents would leave the service, even as separate U.S. government investigations were under way into the incident.

The tawdry episode also took a political turn when presumptive Republican presidential nominee Mitt Romney said he would fire the agents involved.

The Secret Service did not identify the three agents leaving the government or eight more it said remain on administrative leave. In a statement, it said one supervisor was allowed to retire and another will be fired for cause. A third employee, who was not a supervisor, has resigned.

The agents were implicated in the prostitution scandal in Colombia that also involved about 10 military service members and as many as 20 women. Security clearances were revoked for all the Secret Service employees who were involved.

“These are the first steps,” said Rep. Pete King, R-N.Y., chairman of the House Homeland Security Committee, which oversees the Secret Service. King said the agency’s director, Mark Sullivan, took employment action against “the three people he believes the case was clearest against.” But King said, “It’s certainly not over.”

The scandal, which has become an election-year embarrassment for the Obama administration, erupted last week after 11 Secret Service agents were sent home from Cartagena on Colombia’s Caribbean coast after a night of partying that reportedly ended with at least some of them bringing prostitutes back to their hotel.

The special agents and uniformed officers were in Colombia in advance of President Barack Obama’s arrival for the Summit of the Americas.

In Washington and Colombia, separate U.S. government investigations were already under way. King said he has assigned four congressional investigators to the probe.