Police have released further details about the assault, and believed stabbing, on Saturday.
A force spokesman said the two victims remain in hospital and the three people arrested remain in custody.
They said: “The altercation itself is believed to have taken place at a flat in Trinity Street and we believe there may be a connection to a car which had been parked in the PC World car park.”
They added a further update is set to appear this morning (Monday).
Anyone who was in the area of Trinity Street prior to 7pm on Saturday evening and saw anything suspicious is asked to contact Lincolnshire Police in confidence on 101, quoting incident 388 of September 12.