The study released Monday by the security firm Emsisoft said ransomware attacks — which encrypt and disable computer systems while demanding a ransom — affected 113 federal, state and municipal governments, 560 health facilities and 1,681 schools, colleges and universities last year.

“The attacks caused significant, and sometimes life-threatening, disruption: ambulances carrying emergency patients had to be redirected, cancer treatments were delayed, lab test results were inaccessible, hospital employees were furloughed and 911 (emergency) services were interrupted,” the report said.