The Federal Bureau of investigation is stumped, and it's seeking the public's assistance in nabbing those responsible for severing fiber-optic cable throughout the San Francisco Bay Area.

In one of the latest incidents, happening in the Oakland suburb of Walnut Creek, cable responsible for landline and wireless AT&T customers was severed on June 9. AT&T is offering a $1,000 reward for info leading to the conviction of those responsible. At least 10 incidents, beginning last July in Berkeley, have knocked out various California telecom services.

Here are the dates and locations, according to the FBI:

7/6/2014, 9:44pm near 7th St. and Grayson St. in Berkeley. 7/6/2014 11:39pm near Niles Canyon Blvd. and Mission Blvd. in Fremont. 7/7/2014 12:24am near Jones Road and Iron Horse Trail in Walnut Creek. 7/7/2014 12:51am near Niles Canyon Blvd. and Alameda Creek in Fremont. 7/7/2014 2:13am near Stockton Ave. and University Ave. in San Jose. 2/24/2015 11:30pm near Niles Canyon Blvd. and Mission Blvd. in Fremont. 2/24/2015 11:30pm near Niles Canyon Blvd. and Alameda Creek in Fremont. 6/8/2015 11:00pm. near Danville Blvd. and Rudgear Road in Alamo. 6/8/2015 11:40pm near Overacker Ave and Mowry Ave in Fremont. 6/9/2015 1:38pm near Jones Road and Parkside Dr. in Walnut Creek.

"Anyone who may have been in these areas during these times and saw anything either suspicious or related to normal telecommunications maintenance is urged to contact the FBI," said Greg Wuthrich, an FBI special agent. "The individuals may appear to be normal telecommunications maintenance workers or possess tools consistent with that job role."

The bureau said that there was "no indication" that these 10 incidents were related to the still-unsolved 2013 sabotage of a San Jose-area Pacific Gas & Electric substation. AT&T fiber-optic cables were cut and a sniper's bullets knocked out 17 transformers in that situation.

Last year, the Federal Energy Regulatory Commission accidentally released a document outlining areas where the nation's electrical grid was susceptible to a terror attack. The Wall Street Journal, citing the data, reported that an attack on nine "key" substations could cause power outages nationwide.

The FBI's online tip-line is at tips.fbi.gov.