！
Call the police!
Literal
Police [object-を] call-[request-て]!
An urgent te-form imperative — 呼んで! The bare te-form is direct and used for urgency or close speech. The full polite form would be 警察を呼んでください. Note that 警察 refers to the police (the institution); calling 'a police officer' specifically would be 警察官. An emergency-relevant phrase to know.