BOSTON — Boston Police are warning bar-goers and late-night revelers to watch their backs — and their phones — after a wave of slick, high-stakes thefts sweeping Downtown, Back Bay, Fenway, and the Seaport.

The crooks aren’t just swiping devices. They’re cracking into victims’ Apple Pay, Venmo, crypto wallets, and even DraftKings accounts — draining thousands before the night is over.

According to BPD, the thieves strike between 11:30 p.m. and 2 a.m., when crowds pour out of clubs and bars. Their tactics range from smooth to sinister: snatching phones during or after ride shares, offering “friendly” rides only to rob victims, watching over shoulders to capture passcodes, pretending to borrow phones for calls or photos, and in some cases resorting to threats or outright violence.

Once the phone is in their hands, the financial bleed begins. In some cases, suspects gained access to Apple IDs and drained connected debit and credit cards. Others targeted betting apps and cryptocurrency wallets, cashing out before victims even knew what hit them.

Police are urging residents and visitors to lock down their devices and never, under any circumstances, hand their phones to strangers.

Anyone with information — photos, videos, or tips — is asked to reach out anonymously via CrimeStoppers at 1-800-494-TIPS, by texting “TIP” to 27463, or online at the BPD CrimeStoppers website.

The department emphasized that anonymity is guaranteed for anyone helping the investigation.