A South Carolina man who the authorities say ambushed law enforcement officers, fatally shooting a police sergeant and wounding six other officers, had 129 guns stockpiled at his home and fired about 39 rounds at officers, a local sheriff said on Tuesday.

Those details were offered at a news conference as law enforcement officials said they had completed processing what the sheriff, Leon Lott of Richland County, S.C., said was “one of the worst” crime scenes he had ever seen. For days, local and federal investigators combed the gunman’s home — and six blocks around it — where deputies arrived earlier this month expecting to serve a search warrant and interview the man’s son in connection with a criminal sexual assault case.

The tallies they took were grim: About 390 shell casings from bullets fired by the police; three different weapons — a pistol and two military-style assault rifles — used by the gunman to fire on the authorities; and an additional 126 guns he did not fire, but apparently legally owned.

“Just going inside the house is chilling,” Sheriff Lott said. “The officers had no chance whatsoever.”