police = members of Police force

• The police is here ❌
• The police are here 

1. The police are investigating the fraud allegations against him.
2. Police say that they have arrested the chain snatcher.
3. When someone is killed, the police have to be informed.
   

The word police always follows a plural verb.

BUT,

• The police officer is here.
• The policeman says that he cannot manage the situation single-handed.
• The policewoman is after the chain snatcher.
• 15 more police officers were posted in the riot-torn city.