(CNN) -- Seven Royal Marines were arrested Thursday on suspicion of murder involving an incident in Afghanistan in 2011, a British Ministry of Defence spokesman said.
The incident occurred after an engagement with an insurgent, and no civilians were involved, the spokesman said.
"The investigation will now be taken forward and dealt with by the Service Justice system," the spokesman said. "These arrests demonstrate the Department and the Armed Forces' determination to ensure UK personnel act in accordance with their Rules of Engagement and our standards."
The military will review the serious incident to identify lessons learned, the spokesman said.
The ministry wasn't releasing further details Thursday, the spokesman said.