A towering slab of rock broke from a cliff and toppled on to pleasure boaters drifting near a waterfall on a Brazilian lake on Saturday and officials said at least six people died. Minas Gerais fire department commander Edgard Estevo told a news conference that in addition to the dead, as many as 20 people may be missing, and said officials are seeking to identify them. Officials earlier said at least 32 people were also injured, though most had been discharged from hospitals by Saturday evening. Video images showed a gathering of small boats moving slowly near the sheer rock cliff on Furnas Lake when a fissure appeared in the rock and a huge piece toppled directly on to at least two of the vessels. Estevo said the accident occurred between the towns of Sao Jose da Barra and Capitolio, from which the boats had left. The press office of Minas Gerais state told the Associated Press that the fire department had deployed divers and helicopters to help. Minas Gerais governor Romeu Zema sent messages of solidarity with the victims via social media. Furnas Lake, called the “sea of Minas”, is a popular tourist draw in the area roughly 420km (260 miles) north of São Paulo. The state of Minas Gerais has been experiencing heavy rains that have forced almost 17,000 people out of their homes due to flooding, according to the state civil defence. Officials suggested that the earlier rains could have contributed to the wall coming loose. The Brazilian Navy, which also helped in the rescue, said it would investigate the causes of the accident.