I’m thinking by the end of the day we should have an idea who did this.

(CBS News) —  Law enforcement officers investigating the Boston marathon bombings searched the suburban apartment of a man being questioned in connection with the attack late Monday into early Tuesday, CBS Boston station WBZ-TV reports..

CBS News senior correspondent John Miller reports the man is a Saudi national currently under guard at an area hospital. He was seen running from the explosion, and a civilian chased him down and tackled him. He was turned over to Boston police and was being interviewed by the FBI. He was being cooperative and denying any involvement.

“This could mean a lot, or this could mean very little,” Miller said. “It’s too soon to call him a suspect.”

Massachusetts State Police confirm to The Associated Press that a search warrant related to the probe was served Monday night in Revere, Mass., but provided no further details.

Some investigators were seen leaving the apartment building early Tuesday carrying brown paper bags, plastic trash bags and a duffel bag.