HAYWARD — Police are warning residents to be wary after a recent increase in daytime burglaries, in which the criminals knock on the front door to see if anyone is home, then break in through the rear of the home if no one answers.

Lt. Sheryl Boykins said there were 138 burglaries in South Hayward during a three-month span that ended in May — a 70 percent increase over the same period last year.

Boykins said police have made numerous arrests of burglary suspects, and while the number of incidents has dropped, there are more teams operating.

Many of the crimes follow a similar methodology, she said: They happen during the week, between 9 a.m. and 3 p.m. Someone rings the doorbell or knocks, and if there is no answer, they move to the rear yard and force entry into the home.

The intruders take electronic devices, money, jewelry, and search for cash and credit cards. Often a pillowcase is missing, and Boykins said it's likely they use it to sack the purloined goods. They then casually leave the area, most likely in a getaway vehicle.

Earlier this week, San Leandro police arrested seven people after a neighbor spotted them committing a similar burglary.

Hayward police Lt. Reid Lindblom said an arrest recently was made in the Hayward hills after neighbors spotted suspicious activity and called 911, and added that vigilance by neighbors is the best defense.

"We have some already very active neighborhood groups up on the hill," Lindblom said. "If they are having issues with a certain kind of crime, they organize themselves very quickly."

Police have passed out fliers in areas that have seen the most burglaries — including Fairway Park and West Palma Ceia — and they will have a meeting on safety issues and concerns at 7 p.m. Tuesday at the Southland Mall meeting room, Boykins said.

Residents should keep an eye out for door-to-door solicitors who don't appear legitimate, as well as occupied parked cars, she said. Residents also should acknowledge knocks by speaking through a locked door, and let neighbors know when they are going on vacation.

For more information, contact Boykins (South District commander) at 510-293-7296 or Lindblom (North District commander) at 510-293-7043.

Eric Kurhi covers Hayward. Contact him at 510-293-2473. Follow him at Twitter.com/erickurhi. Read our blog at www.ibabuzz.com/hayword.