Mr Grunshaw tweeted: "I understand the concerns that the public have raised after the incident at Runshaw College and I have been fully briefed by the Chief Constable and kept fully updated as the investigation progresses.
"My thoughts are with those affected by what happened yesterday and support for anyone who needs it is available through (Lancashire Victim Services) and (Nest Lancashire).
He added: "@LancsPolice do an extremely important job in protecting our communities and carrying out robust enforcement, but it is ultimately through early action and prevention work that we can most effectively tackle knife and serious violence."