Bugi is said to be the third-biggest river in Garo Hills.
Meghalaya has been hit by intense rain, flood and landslide this year that has left several people dead and displaced many more.
Three members of a family and a 2-year-old child were buried alive in landslides in two different places in the state's Garo Hills in the early hours of Thursday.
A video shot by locals in the South Garo Hills captured the situation in the region, showing a bridge being washed away.
The bridge over the Bugi River connected Ruga to Jejika village. Bugi is said to be the third-biggest river in Garo Hills.
The India Meteorological Department (IMD) has warned of isolated extremely heavy rainfall (more than 204.5 mm) in Arunachal Pradesh on June 10-11, and Assam and Meghalaya during the next five days.
Senior IMD scientist R K Jenamani said the monsoon touched the Kerala coast on May 29 and covered south and central Arabian Sea, Kerala, parts of Karnataka and Tamil Nadu and the entire northeast between May 31 and June 7.