A series of unrelated bomb and graffiti threats at several school campuses in the past week have police in three East Bay cities on alert.
On Wednesday about 2 p.m., the Fremont school district put Thornton Jr. High School on lockdown for roughly 30 minutes after district officials received a phone call about a bomb threat there, police said.
Police checked the school and lifted the lockdown at 2:35 p.m., but authorities were continuing to investigate.
Meanwhile, police in Pleasanton added extra patrols at Foothill High School this week after a graffiti threat was found in a girls bathroom.
Foothill High Principal John Dwyer sent a note to parents and staff about "a possible threat toward the school," after the graffiti was discovered.
Pleasanton police could not immediately be reached for comment Wednesday.
In Tracy, extra police and security were added at Kimball High School, possibly until the end of the week, after two students last week found threatening graffiti in a girls bathroom.
District spokeswoman Jessica Cardoza declined to provide details about the message, but said it did not contain a threat to a specific group of people and did not mention a gun or shooting.
Students shared photos of the graffiti over the weekend and rumors about a threatened shooting began. There has been no violence, but the school was flooded with concerned calls from parents Monday, Cardoza said.
Not far across town, Tracy High was evacuated Wednesday afternoon after two threatening notes, including one about a bomb, were found in two boys bathrooms. School officials are reviewing security camera footage and police dogs were called in to help officers search the school. School will resume Thursday if police give the all clear, Cardoza said.
"These types of threats do come in, and we treat them with the utmost seriousness. We take them very seriously and leave no stone unturned," she said.
Staff writer Katie Nelson contributed to this report. Reach Kristin J. Bender at email@example.com. Follow her at Twitter.com/kjbender. Reach Daniel Jimenez at firstname.lastname@example.org. Follow him at Twitter.com/dmjreports.