Authorities said they received a call of shots fired at a home on the 8600 block of Garfield Avenue at about 8:30 a.m.
"We had three different neighbors call us up that they heard shots being fired," said Lt. Russell Reinhart of the Huntington Beach Police Department. "They also heard arguing. It was quiet after that, then they heard another gunshot."
Reinhart said police tried to make contact with the residents inside the home, but were not able to communicate with anyone.
A couple in their 50s resides in the home, police said.
A SWAT team made entry into the home and searched the first floor without result.
The SWAT team found two deceased adults in an upstairs bedroom who appear to have been shot.
Police at the scene suspect the incident was a result of a murder-suicide.
Streets in the area were closed due to the investigation.