SEATTLE — The oldest two of three homeless teen brothers suspected in a deadly, drug-related mass shooting at a Seattle homeless camp last week have been charged as adults.

All three boys — ages 13, 16 and 17 — were charged with first-degree murder and assault and only the youngest will face the allegations in juvenile court, King County Prosecutor Dan Satterberg said Thursday.

The shooting came at a homeless encampment in a wooded area under Interstate 5, a few blocks from Safeco Field, where the Mariners play.

It left two people dead and three wounded and has prompted calls to shut down the encampment, a lawless place that Satterberg noted ‘‘is called ‘The Jungle’ and lives up to its name.’’

The teens had been living in tents nearby and told one police informant that they went into the encampment on Jan. 26 to collect a $500 drug debt owed to their mother.

They were armed with two handguns , Satterberg said. The two older boys had a history of juvenile offenses and were familiar to authorities with the Department of Social and Health Services, Satterberg said.

‘‘They were wards of the state, but they had run from every placement DSHS had arranged for them,’’ he said, adding the teens ‘‘moved with ease’’ in the marginalized environment of the homeless camp.

Associated Press