Snook was arrested at his east side home on Martha Avenue on Wednesday, shortly after 5 p.m.
Several officers started searching the semi-detached white bungalow, which has a For Sale sign out front, shortly before 10 p.m.
Within a few minutes, they removed a laptop bag and other items.
No details have been released and no charges have been laid.
RCMP and Saint John Police Force officers at the scene declined to comment and officials could not immediately be reached.
Cpl. Jean-Marc Paré, a member of the RCMP’s Internet Child Exploitation Unit, confirmed on Thursday his unit is involved in the investigation
Mayor Mel Norton told CBC News Snook was taken in for questioning.
"I don’t know any of the details as to why," he said.
"We don't know any of the plans or intentions of police at this point."
Snook, who serves in Ward 3, is the director of the non-profit group Saint John Inner City Youth Ministry.
The mayor said he was advised of the arrest after the fact by Saint John Police Chief Bill Reid and Deputy Chief Bruce Connell.
"It's a surprise," Norton said. "Obviously, as I say, it's a very serious matter for him. Any time law enforcement takes you for questioning, that's a serious personal matter."
It's not yet clear what, if any impact Snook's arrest will have on council business, said Norton.
Council's next regularly-scheduled meeting isn't until Monday, he said.
"We've notified all the members of council of the information we have at this point, which is the information I've just outlined.
"Beyond that, we're just waiting to certainly hear how this develops."
Snook was elected to council in 2008 and re-elected in May 2012 with 2,303 votes.
Snook was one of only two incumbents who successfully sought re-election.
Ward 1 Coun. Bill Farren, who was also re-elected, said he was shocked by Snook's arrest.
"Total shock," he said. "I imagine anybody that's hearing it is probably doubting it."
"Well, I mean, you know, everybody's innocent until proven guilty," he stressed.
Farren described Snook as a "stand-up fellow that's stood up for the rights of individuals and groups."
"He's always provided good discussion and debate at the committee of the whole and around the horseshoe. I consider his input quite valuable."
Snook's Facebook page says he has been director of the youth ministry group for 13 years.
"He is especially known for his work with the popular youth programs Kids Zone and the Chicken Noodle Club hot lunch program," it states.
Snook is a former board member for the Boys and Girls Club and has volunteered with several other organizations over the years, including PRO Kids (Positive Recreational Opportunities for Kids), National Child Day committee, and the South End Little League executive, according to his Facebook profile.
His work in the community was recognized in 2003 with the YMCA Canada Peace medal.