"...A witness to the explosion named Grossman claimed to have seen a pale yellow Mercury car with a Ryder T\truck behind it pulling up to the Federal Building. Mr. Grossman further claimed to have seen a woman on the corner waving to the truck. ATSAIC McNally noted that this face is significant due to the fact that the security video shows the Ryder truck pulling up to the Federal Building and then pausing (7-10 seconds) before resuming into a slot in front of the building. Is is speculated that the woman was signalling the truck when a slot became available..."
Yep. See also the report via AP, at this post and responses.e