(STMW) — Two brothers who were found dead at the site of a townhouse under construction Tuesday morning in southwest suburban Lockport were shot, autopsies have found.

David Ceja-Sanchez, 35, and Marco Ceja-Sanchez, 37, each suffered a single fatal gunshot wound, the Will County coroner’s office announced Wednesday evening.

READ MORE: Mars Wrigley Says It Will Move Most Operations Out Of Its Plant On Chicago's West Side Over Next 2 Years

The Aurora residents were discovered when their coworkers showed up at the work site about 6:30 a.m. in the 16100 block of Coneflower Drive, according to Lockport police and the coroner’s office.

READ MORE: Uber Driver Shot On Eisenhower Expressway

Their deaths are being investigated as a double homicide, authorities said. No one was in custody.

The Will-Grundy Major Crimes Task Force is assisting with the investigation.

MORE NEWS: Chicago White Sox Plan To Take Action After CBS 2 Investigators Expose Parking Scam Outside Sports Venues: Fans Getting Ripped Off By Conmen, Then Hit With Parking Tickets

(Source: Sun-Times Media Wire copy; Chicago Sun-Times 2016. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)