ST. PETERSBURG, Fla. (WFLA) — St. Petersburg police detectives are investigating a rash of cell phone thefts in the downtown entertainment district.

The agency reports 31 thefts between Feb. 5 and February 27. Department spokeswoman Yolanda Fernandez explains it is a crime of opportunity.

“Any time there is a crowd. So if there happens to be, mostly on the weekends is when we are seeing it, but during the week too,” said Fernandez. “Especially now when we are getting into the spring break season and we know a lot of young people are going to be coming to the downtown area. “

Investigators say the crooks targeted The Crafty Squirrel, Pour Judgement, 260 First, Mandarin Hide and The Estate.

One victim, who didn’t want to be identified, was at The Estate celebrating a friend’s birthday when it happened.

“We were all out at The Estate doing the ‘Cha-Cha Slide’ and then the next thing I know, I go to get us a few drinks and [my] phone’s gone,” the man said. “That night, I went around asking everyone if they had found a lost phone and that’s when other people were saying that their phones were lost. But they weren’t really lost, they were pick-pocketed.”

Detectives believe the thieves, in most cases, bumped into the victims in crowded venues and stole their phones.

In some cases, people also had pockets for credit cards and cash attached to their phone cases. The crooks got that as well.

“You’re in a crowded area, you get bumped, your cell phone is gone – you may not even realize if you dropped it, if it was stolen or you left it somewhere,” said Fernandez. “It takes you a while to even report it.”

Police say the best advice is to protect your phone and other valuables. Don’t keep your phone in a back pocket where half of it is sticking out, keep it in a front pocket if possible. If you are a woman and have your phone in your purse, make sure that purse is zipped up.

Rob Rivera is one of the general managers at the Crafty Squirrel. He says he regularly gets calls about lost cell phones and other valuables, but one weekend in February was different.

“Typically on a Saturday morning, Sunday morning – you get a lot of calls about phones, ‘I lost my phone, I lost my wallet, I lost this,'” said Rivera. “And so one morning it just built up. There was probably a good 13 calls.”

Rivera does have surveillance cameras and the video was recording the night the crooks hit. But it’s hard to make out who is doing what.

“Everyone’s drinking, everyone is having a good time and dancing and even if someone is just standing there, there’s people in the way, I can’t get a clear view. It’s nearly impossible,” said Rivera. “It’s a needle in a haystack.”