The LFR tech was used on Thursday close to East and West Croydon train stations.
The men, aged between 19 and 49 years, were arrested for offences including rape, robbery and GBH.
All seven remain in police custody.
The LFR tech was used on Thursday close to East and West Croydon train stations.
The men, aged between 19 and 49 years, were arrested for offences including rape, robbery and GBH.
All seven remain in police custody.