This photo provided by the St. Lucie county Sheriff's office on Monday, July 18, 2011, shows Tyler Hadley, 17, of Port St. Lucie, Fla. Hadley is accused of beating his parents to death with a hammer and then throwing a party. He is being held on two counts of first-degree murder in the deaths of his parents, Blake and Mary-Jo Hadley. The bodies were discovered early Sunday morning after police received a tip.. (AP Photo/ St. Lucie county Sheriff's office)

A Florida teen is accused of posting a Facebook invite for a house party, killing his parents with a hammer and then hosting dozens of people while the adults' bludgeoned bodies were locked in the master bedroom.

The bodies were discovered by police early Sunday, and 17-year-old Tyler Hadley of Port St. Lucie is charged with two counts of first-degree murder. Police believe the adults were struck on their heads and torsos the previous day sometime after their son posted on Facebook to tell friends about the party.

Investigators believe Blake and Mary-Jo Hadley were attacked outside their master bedroom and the bodies were moved into the bedroom and the door locked.

The teen was being held without bond at a juvenile detention center in Fort Pierce and wasn't clear whether he has an attorney.

As many as 60 people attended the party Saturday in the community about 50 miles north of West Palm Beach, according to Port St. Lucie Police spokesman Tom Nichols. They were loud enough to prompt a noise complaint and a visit by police officers. When they arrived at 1:30 a.m. Sunday to warn about the noise, the party was already breaking up, Nichols said.

Then, police said, they received a tip that a slaying may have taken place. They returned to the home at 4:20 a.m., finding the bodies covered with towels, files, books and other household items, and the hammer between them.

The mother, 47, was an elementary school teacher. The father, 54, worked for Florida Power and Light.

Autopsies were underway, but police said they believed they died of blunt-force trauma.

Hadley had attended St. Lucie West Centennial High School, according to police, but had not graduated. They said they did not know what the motive was.