Rookie defensive end Nick Bosa, the No. 2 pick in the NFL draft, did not finish the 49ers' second offseason practice Tuesday because of a hamstring injury. Head coach Kyle Shanahan said he didn't know the severity of the injury, which Bosa sustained during one-on-one pass-rushing drills. Bosa observed the end of practice and was not being attended to by a member of the medical staff. Last year, Bosa played in just three games at Ohio State due to a core muscle injury, but he said he was fully recovered last month after he was drafted. He also sustained a torn ACL as a senior in high school. Eric Branch is a San Francisco Chronicle staff writer. Email: [email protected] Twitter: @Eric_Branch