At least 10 passengers were killed when a private bus carrying nearly three dozen university staff plunged into a ravine in Raigad district of Maharashtra on Saturday morning, an official said.Raigad Police Control official P.D. Patil said that around 35 staff of Konkan Agriculture University in Ratnagiri, including some women, were on way for a weekend picnic to popular tourist destinations of Mahabaleshwar-Panchgani when the bus fell 500 feet down into the ravine around 9 a.m. near Poladpur.Rescue efforts were severely hampered by heavy rains lashing the Western Ghats, besides poor connectivity in the remote hills in the area."As per preliminary information, at least 10 bodies have been recovered and efforts are underway to rescue others or retrieve more bodies," Patil told IANS.The accident came to notice after one of the injured passengers managed to climb up and alerted the authorities.National Disaster Relief Fund teams from Pune were en route to help villagers and others involved in search and rescue operation.