UPDATE As of 3 p.m., power had been fully restored.
Power went out in the Barron Park area of Palo Alto around 1 p.m. Sunday, impacting about 2,500 customers, according to a tweet from Palo Alto Utilities.
The cause was a Mylar ballon that hit utility wires, the Utilities Department stated.
Crews were working to restore electricity, a task that is expected to take until 4 p.m., the department stated.
A map of the outage can be found on the city's Utilities website.
The map showed that about 22% of customers in the section of the city roughly bounded by Middlefield Road, Foothill Expressway, San Antonio Road and Page Mill/Oregon Expressway, plus the College Terrace and Southgate neighborhoods, were affected.