"Pretty extensive. On D-day, when we came in, Kilo company had to deal with this," said Lt. Col. Brian Christmas. "There are two of them that we found so far."
And there are many more out there. But even when they spot them, the Marines are on strict orders to "go slow" and avoid using heavy weapons or air strikes.
Special Report: Afghanistan
The Taliban is using the local population as a human shield - and it's working. The Marines are taking greater risks to avoid civilian casualties.
They're moving in slowly, trying to flush out the snipers one at a time.
British troops have gone deep into Taliban-controlled areas to find them and U.S. military sources say that two elite teams of Marines are on a similar mission.
More coverage from CBS News Correspondent Mandy Clark:
Marines Reach out to Marjah Population
Marines Drive Into Afghan Stronghold
Marines Engage Taliban on Edge of Marjah
Afghanistan: Life on the Frontline
Still, local residents have been caught up in the crossfire. Major Jim Coffman is a civil affairs officer. He has to meet the victims' families.
"I lifted the sheet and there was a little girl that was dead," Maj. Coffman said. "She was probably about the same age as my youngest daughter."
Everyone - soldiers and civilians - is waiting for the fighting to end. But as long as there are snipers hiding among them, no one here is safe.