"He parked with the passenger's side facing a small brick wall near the front entrance. His shotgun was left leaning against the passenger's side door."

[link to www.courant.com]

Note passenger's side not passenger side.

This wording implies there was a passenger.

That same statement, give by CSP Sgt Cario and others to the Courant, says multiple children were removed by Cario and his men from Room 8 and taken to Danbury in police cruisers.