Three people were hurt — one critically — when a box truck slammed into scaffolding, causing it to collapse in Chelsea on Monday morning, cops said.The 62-year-old driver struck the scaffolding set up on West 29th Street near Eighth Avenue, causing it to fall, around 8:15 a.m., authorities said.Three people were hurt when the structure came tumbling down, police said.One person was taken to Bellevue in critical condition, and the other two in stable condition with minor injuries.The driver stayed at the scene and no arrests were immediately made.There were no building stability issues, the FDNY said....