Federal Bureau of Investigation (FBI) SWAT teams on Thursday conducted a search of the last known address associated with Robert Card, the suspect in a Wednesday night shooting rampage that left 18 people dead in Lewiston, law enforcement sources told CNN.

The sources told CNN that once FBI SWAT teams cleared the house, investigators came in to execute the search warrant, looking for items like computers, notes, weapons and any evidence that might indicate a plan to carry out the shootings.

Card, 40, is facing an arrest warrant for eight counts of murder and should be considered armed and dangerous, police said.

State and local investigators did a similar style entry and search at another location, as well as a search of Card’s car on Thursday, the sources told CNN.

Law enforcement officials returned to the Lewiston shooting suspect’s last known address on Thursday evening, according to CNN teams on site. At least five law enforcement vehicles, including an armored vehicle, were seen at the scene, CNN reported.

A spokesperson with the Maine Department of Public Safety told CNN law enforcement is “not positive Robert Card is in this house,” adding officials are “simply doing our due diligence.”

In Lisbon, investigators recovered a gun on Thursday while searching an abandoned car at a boat launch connected to the suspect, but it hasn’t been determined whether the firearm was used in Wednesday’s shooting rampage, a law enforcement source told CNN.