State Police say a Saugus man will face a citation after allegedly hitting a school bus Thursday morning in the Thomas P. O’Neill Jr. Tunnel, causing lengthy delays as rush hour began.

Just after 6 a.m., a Lexus SUV driven by Thomas P. Wells, 52, crashed into the bus, which was not carrying any children, said State Police spokesman Dave Procopio. Video footage shows that the car rear-ended the left side of the bus, causing it to spin.

All lanes were blocked, and traffic on Interstate 93 was backed up for miles. The 60-year-old bus driver, from Randolph, was not injured, Procopio said.