The United States is condemning the murders of seven Syrian White Helmet civil defense members in rebel-controlled Idlib province.
State Department spokeswoman Heather Nauert calls the murders sad and horrifying.
"These cowardly acts of masked men took the lives of civilian volunteers who work tirelessly as first responders in order to save lives in incredibly dangerous environments," she said in a statement.
Nauert says the U.S. sends it condolences to the families of those she calls "heroes," and hopes they can find justice.
The White Helmets say unidentified gunmen shot the seven members dead during a raid on their base Saturday in the town of Sarmin, west of Idlib city. Two vans, some white headgear that identify the volunteers, and walkie-talkies were stolen.
No one has claimed responsibility. Idlib province is controlled by the Syrian rebel group called Hayat Tahrir al-Sham. It condemned what it calls an "ugly crime," vows to hunt down the killers and promises to protect the White Helmets.
The White Helmets are Syrian civil defense workers who volunteer to rush in with no hesitation to pull civilians out of bombed buildings in rebel-held areas.
A number have been killed in the line of duty. They received global renown after they were nominated for the 2016 Nobel Peace Prize.
Despite criticism they back the rebels against the Syrian government, the White Helmets insist they take no sides in the war.