1 agent killed, 2 officers hurt in shooting aboard Amtrak train

One Drug Enforcement Administration agent was killed and two other officers were injured in a shooting on an Amtrak train that was stopped in Tucson, Arizona, authorities said.

Officers boarded the train Monday morning to perform a routine check for illegal guns, money and drugs and encountered two people on the second level of the double-decker Amtrak car, Tucson police said.

One individual was detained, but a second person revealed a handgun and opened fire, police said.

The DEA agent who was killed was identified Tuesday as DEA Group Supervisor Michael Garbo. He joined DEA in 2005 and "served honorably for more than 16 years as a Special Agent and Group Supervisor combatting criminal drug traffickers from the Nogales corridor to Kabul, Afghanistan," DEA Administrator Anne Milgram said in a statement.

"Group Supervisor Garbo's operational expertise, mentorship, and leadership were legendary in the Tucson community," Milgram said. "Across DEA, Group Supervisor Garbo was universally loved and respected for his leadership, and for his unrelenting passion to protect the safety of the American people. Above all else, he was a devoted and loving father and husband. DEA mourns the loss of our beloved colleague."

Another DEA special agent who suffered multiple gunshot wounds during the incident is in stable condition, DEA said Tuesday.

A Tucson police officer who was on the platform heard the gunfire and ran onto the train, at which point he was shot, police said. That officer is also in stable condition, police said.

After exchanging rounds with police, the suspected gunman barricaded himself in a lower-level bathroom, authorities said. It was later determined that the suspected gunman died, though it is not clear how he died, police said.

There were no reports of injuries to the 137 passengers or 11 crew members, Amtrak said.

The train was en route from Los Angeles to New Orleans and arrived in Tucson at 7:40 a.m. local time, Amtrak said.

ABC News' Nicholas Kerr and Luke Barr contributed to this report.