Va. Code § 15.2-1300.1
A locality may, by ordinance or resolution, authorize its chief administrative officer to arrange for provision of aid to other localities or receipt of aid from other localities in situations where a locality does not declare a local emergency, including approval by the chief administrator of agreements with other localities, subject to availability of resources. In situations where localities declare a local emergency, the provision or receipt of aid may occur pursuant to § 44-146.20. The ordinance or resolution may include terms and conditions deemed necessary by the governing body for participation in such aid and shall set forth the scope of the chief administrator's authority, including the type of aid that may be provided or received, or may generally authorize participation in provision or receipt of any type of aid including personnel, equipment, or other resources for public purposes. Prior to providing or receiving aid, the chief administrator shall conduct an assessment of available resources and shall consider establishing terms for the supervision of personnel, the term of deployment, payment or reimbursement of costs, and verification of insurance coverage.
The ordinance or resolution may allow for the participation of volunteers and, with approval of the constitutional officer, constitutional officers and their staffs. Deployed personnel acting pursuant to the ordinance or resolution of the governing body shall have the same authority and immunity in other localities as in the locality where they are employed or volunteer.
Va. Code § 15.2-1300.1