A 23-year-old man was shot dead and his younger brother badly injured in an early morning home invasion in the inland Mendocino County community of Redwood Valley, the Mendocino County Sheriff's Office said Friday.

The slain man has been identified as Celso Madueno, authorities said. His brother is Abel Madueno, 19.

Detectives were working furiously to track down leads that might shed light on what prompted the bloodshed at a rural home among vineyards about 10 miles north of Ukiah.

Authorities said two armed men — at least one of them wearing a hood and a bandana over his face — forced their way into the East Road house sometime before 2:44 a.m. Friday for unknown reasons.

Abel Madueno, his parents and grandparents, and a younger child live in the house, Lt. Greg Van Patten said.

Celso Madueno lived in a nearby granny unit on the property and came in when he heard the commotion, Van Patten said.

Multiple rounds were fired. Celso Madueno was hit more than once and was pronounced dead at the scene, authorities said.

The initial call to 911 indicated the younger man also had been killed, but deputies and emergency personnel found him alive, conscious and talking, Assistant Redwood Valley Fire Chief Pete Brown said.

He was taken by ground ambulance to Ukiah Valley Medical Center and later to an out-of-county hospital, and was expected to recover, Brown and Van Patten said.

Van Patten said deputies found marijuana growing on the property, but he cautioned against assuming it had any connection to the gunfire.

"It's way too early in this investigation to put our finger on what the motive is," he said Friday morning. "Anything is a possibility at this point, and we're exploring all avenues."

It was unclear if the gunmen said anything to residents of the home or the victims before they opened fire, Van Patten said.

There were no immediate indications that anything was stolen.

A witness said one of the intruders wore a red hooded sweatshirt and a black bandana partially obscuring his face, authorities said.

A neighbor saw a black Cadillac Escalade SUV leave the area after the shooting, heading north on East Road, Van Patten said.

Anyone with information about the shooting can call the sheriff's tip line at (707) 234-2100. Callers may remain anonymous.