The impassioned debate surrounding California legislation to remove the personal-belief exemption for vaccinations has bubbled over into threats against lawmakers and heightened security measures for at least one state senator.

Sen. Richard Pan, a Sacramento Democrat who introduced SB 277, said the in-house law enforcement unit has provided him with extra security in recent weeks, after his office began receiving alarming phone calls, e-mails and Facebook comments from opponents of the bill.

“They’re basically trying to silence us,” Pan said. “It’s disturbing.”

The messages range from images depicting Pan as a Nazi to posts on his Facebook page calling for him to be “eradicated” or hung by a noose. Pan said his staff has forwarded all of the threats to the Senate Sergeant-at-Arms office, as is procedure, which has assessed them and responded as needed. Additional guards attended a community forum last month, for example, after bill opponents discussed throwing things at Pan.