KILLEEN, Texas (CNN) — The U.S. Army is asking for the public’s help in finding 23-year-old Fort Hood soldier Elder Fernandes, according to a statement from Fort Hood in Texas.

“The 1st Cavalry Division is actively attempting to locate Sgt. Elder Fernandes who has gone missing,” the statement said. “Our primary concern is for his health and well-being.”

Fernandes is about 5 feet, 4 inches tall, and weighs approximately 133 pounds, according to the Killeen Police Department, which is investigating his disappearance. Police said he was last seen wearing black army shorts and a t-shirt with red athletic shoes.

According to Killeen police, Fernandes’ family said the 23-year-old was last seen on Monday afternoon by his staff sergeant when he was dropped off at his home in Killeen.

“This is very, very unusual,” Isbael Fernandes, the missing soldier’s aunt, told CNN affiliate KTRK. She last spoke with her nephew last Friday morning and said that he’d called his mother on Sunday. Fernandes promised to call again on Monday, his aunt said.

“Monday came and went and he didn’t call, and he didn’t answer calls from anyone else. Tuesday, no calls and my sister ended up flying down there yesterday, and still we haven’t heard from him,” she told KTRK.

According to Fort Hood, Fernandes is a chemical, biological, radiological and nuclear specialist assigned to the 1st Cavalry Division Sustainment Brigade. Finding him is a “top priority for the Division,” Fort Hood’s statement said.

“We have completed a search of the entire division area, to include motorpools, parking lots, and headquarters buildings,” the statement said, “and the unit is in contact with the Soldiers Family [sic], the U.S. Army Criminal Investigation Division and civilian law enforcement agencies to help find him as we continue our search.”

Anyone who has seen Fernandes or knows where he might be is asked to contact Killeen police, the Fort Hood Military Police or US Army Criminal Investigation Command (CID).

This year, there have been a series of incidents in which Fort Hood soldiers have vanished and died, perhaps the most high-profile of which was the murder of Spc. Vanessa Guillen. The main suspect in her disappearance — another Fort Hood soldier — killed himself when he was confronted by investigators, according to CID.

In the wake of her death, the Army announced an independent review board made up of five civilians who would review the “command climate and culture” at Fort Hood.

Some soldiers have died under mysterious circumstances, including Pvt. 2nd Class Gregory Scott Morales, whose skeletal remains were found in a Killeen field in mid-June — 10 months after he’d vanished. Fort Hood said in a statement at the time that foul play is suspected in his death.