Two youths were chased and arrested inside a busy shopping centre after allegedly stealing a young boy's mobile phone.
The youngster was shopping in Uxbridge High Street at about 4.30pm on Monday with his mother when a youth pushed him and took the mobile phone from his pocket.
Four youths ran off down the High Street and past police officers, who gave chase and caught two of them.
Ten minutes later, two others were seen close to The Chimes shopping centre. When they realised they had been spotted by police they ran off through the shopping centre.
Five police officers and an off-duty CID officer from Southall gave chase, and arrested them in front of stunned customers in the O2 store.
Emma-Louise Robinson, a shopper, said: "I was standing there looking at mobile phones then suddenly the police ran in and grabbed these two boys who had just come in."
PC Mike Smooker, a Hillingdon Police crime prevention officer, said: "People should always stay alert and be aware of what is going on around them at all times.
"Even when on the phone it is important to know what is going on."