Sam Springsteen, 25, took the civil service exam in March, the Jersey Journal reported. Springsteen has served as a volunteer firefighter in Colts Neck since 2014.
In her post, Scialfa expressed pride and a touch of motherly concern for her son, who bears a strong resemblance to his rock-icon dad.
"You followed your dreams ... stay safe ....love your brave heart", she wrote.
The Division of Fire in Jersey City is the present incarnation of the city's organized fire service, which began nearly 200 years ago, the agency said on its web page.
The more than 600 members who serve the state's second-largest city answered more than 24,000 calls in 2018.
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