UK police are hunting for two men after an unknown gas was released on a tube train in London.
People have been treated for coughing and breathlessness after the attack at Oxford Circus this morning.
Officers were called to the incident at Oxford Circus station just after 9 am this morning.
They've released CCTV images - and believe those pictured could help with the investigation.
A number of people were treated at the scene for coughing and a lack of breath.
Their symptoms suggest it was CS gas, more commonly known as tear gas - but there's no further concern for their health.