St. Petersburg electronics maker Jabil Circuit Inc. is shutting its Massachusetts plant in Billerica and laying off 300 workers there. The closure will start in May and wrap up by October, according to the Boston Globe. The Billerica plant opened in 1999. Jabil plant manager Bill Frake said the deepening global recession has reduced demand. "You can see what's happening out there in the economy, can't you?" Jabil in January said it will lay off 3,000 workers. Company spokeswoman Beth Walters told the Globe that nearly all domestic layoffs will come at the Billerica plant, which is the only Jabil facility to be completely shut down. Jabil estimates the cutbacks will save the company $55 million a year.