BAGHDAD, Iraq (CNN) -- A massive search was under way Saturday for two U.S. soldiers who went missing during a checkpoint attack in Iraq.
Another soldier was killed in Friday's attack at a canal crossing near Yusufiya, about 20 miles southwest of Baghdad.
Yusufiya is part of Iraq's "Triangle of Death," where insurgents are active and there is widespread lawlessness.
When the canal checkpoint was attacked at about 7:55 p.m. (11:55 a.m. ET) Friday, soldiers at a second checkpoint nearby heard an explosion and small-arms fire, Maj. Gen. Willliam Caldwell said Saturday.
They tried to contact the soldiers at the canal and called in a quick-reaction force after they got no response. Reinforcements arrived within 15 minutes and found one soldier dead and the other two missing, the general said.
The names of the soldiers are being withheld until their relatives are notified.
U.S. and Iraqi troops cordoned off the area, shutting down civilian traffic "in a concerted effort to focus the search and prevent the movement of suspects out of the area," Caldwell said.
Helicopters and unmanned aerial vehicles were sent in to help with the search.
Divers were also deployed to search waters at the canal crossing near the Euphrates River.
Three raids were conducted Friday night and another was conducted Saturday morning, Caldwell said, and coalition troops have enlisted the help of local leaders and civilians.
"We are using all available assets," Caldwell said. "We never stop looking for our service members until their status is definitively determined and we continue to pray for their safe return."
Caldwell also highlighted the case of another soldier missing in Iraq, saying the military is still looking for Sgt. Keith Matthew Maupin, who disappeared in April 2004 after his convoy was attacked near Baghdad International Airport.
Like the two soldiers who went missing Friday, Maupin's initial status was "whereabouts unknown." The military changed the Ohio soldier's status to "missing-captured" after the Arabic-language TV network Al-Jazeera showed a videotape of Maupin being held captive by insurgents.