The Congress office was attacked in the wee hours yesterday and the main door of the building was partially burnt, they said.
A newspaper transport vehicle, a police requisition bus and another vehicle were attacked with petrol bombs in Nongmynsong and Umiam Lake areas respectively in the district last night. All three vehicles were damaged.
The Ri-Bhoi district administration has imposed prohibitory orders under section 144 CrPC preventing assembly of five or more persons at a public place.
The attacks came days after five Khasi Students Union leaders were arrested for allegedly leading an arson attack at a railway construction site last month in protest against the railway project in Ri-Bhoi district.
The KSU, an influential students' body here, has aired their opposition to the railway project fearing influx of outsiders in the tribal-dominated state.