My Chemical Romance guitarist Frank Iero has been caught up in a bus crash in Sydney's CBD this afternoon.

A third man was lucky to escape injury. (9NEWS)

Iero and his band mates were arriving at Twitter HQ on Park Street for a performance when a bus crashed into the back of their vehicle before 4pm.

He escaped injury but two other men had to be taken to hospital.

One of the men was airlifted to St Vincent’s Hospital, the other was taken by road. They are both reported to be serious but stable.

One man was airlifted to St Vincent's Hospital. (9NEWS)

The bus was not carrying any passengers at the time and the driver was taken to hospital for mandatory tests.

Investigators at the scene shortly after the crash on Park Street. (9NEWS)

Iero is giving statements to police.