How did the police know about the robbery

The Bank of America is abducted by 6 masked strangers. One of the strangers asked the teller to give them all the money and suddenly the phone of the teller rings (her mother was calling). To avoid any suspicion robber asked the teller to pick her mother phone.

The teller asked her mother "Is there an emergency mother, Call me when you reach home and I will help you with the dinner." and she hangs up.

After 5 minutes, police arrived at the crime scene.

How did the police know about the robbery?

Click here for Answer

On phone, using pause button, the teller messaged to her mother "Emergency mother, call help".

Explanation:
All Except ones in bold is paused by the teller.
Is there an emergency mother, Call me when you reach home and I will help you with the dinner.