sed match pattern and act on x lines after

I'm trying to find a way to comment out a block (multiple lines) in a configuration file. I'd like to match the first line but also act on each line after that.

sed '/\/Some\/Foo\/Bar\/String/' config.file

The following example "code" is what I'm trying to match and comment out. The block will always end with a } but I also know the number of lines after the pattern match so this one would be pattern line + 6.

foo { '/Some/Foo/Bar/String' :
    key1 => value1,
    key2 => value2,
    key3 => value3,
    key4 => value4,
    key5 => value5,
}

Results after sed command

#foo { '/Some/Foo/Bar/String' :
#    key1 => value1,
#    key2 => value2,
#    key3 => value3,
#    key4 => value4,
#    key5 => value5,
#}