The following is a news release from the Montana State Park's office.
"Montana State Parks, stateparks.mt.gov, announced today that Bannack State Park near Dillon, Montana has been closed effective immediately due to a flash flood yesterday late afternoon that damaged historic buildings, roads, trails, bridges, the fire detection system and boardwalks with water and mud.
There were approximately 20 visitors on site at the time, they were evacuated safely.
"The historic Bannack townsite has 60 core buildings, and it is estimated that more than 80% have damage," said Dale Carlson, Park Manager of Bannack State Park.
A majority of the Assay Office next to the Meade Hotel was washed away.
The flash flood came down from Hangman's Gulch through the center of town and is not attributed to Grasshopper Creek overflowing.
Montana State Parks is currently assessing the situation with the State of Montana's Risk Management & Tort Division.
The State Park is closed to the public, and while offers of volunteer assistance is appreciated, at this time until a risk assessment is completed, we have no need for volunteers.
Bannack Days the annual, special event scheduled to occur on Saturday and Sunday, July 20 and July 21 has been cancelled. Montana State Parks staff is contacting organizations and participants with this information.
Bannack State Park is a National Historic Landmark and one of Montana's best preserved ghost towns. Bannack is the site of Montana's first major gold discovery in 1862 and is Montana's first territorial capital. In 2012, more than 32,900 people visited this state park, an increase of 5% over the previous year."