A man has been thrown through the window of Hastings Library by two men who then climbed through the window and continued to assault him.

The attack, in front of shocked library onlookers, took place about 11.15am on Thursday.

Police were now at the scene and were reviewing CCTV footage. Witnesses said they believed it may have been gang-related.

The condition of the assaulted man is unknown at this stage.

A witness at the library told Hawke's Bay Today that a group of five men and one woman with a child were involved in an argument inside the library for about 10 minutes before it escalated.

Those believed to have been a part of the assault had left by the time police arrived, the witness said.