Lagos - Nine people were killed when a passenger boat capsized in Nigeria's commercial hub of Lagos on Sunday, the government said, blaming the accident on overcrowding. Four passengers were also injured in the sinking in the waterfront community of Ilashe, while an unspecified number of others were yet to be rescued, it said. "An unfortunate incident occurred at Ilashe today... arising from overloading of passengers on a banana boat taking off from an illegal jetty which has become a perennial issue of the Lagos state government to rid our waterfront areas of illegal operators," the government said in a statement. "We sympathise with the families of the deceased as nine lives were lost in the mishap and four people (are) receiving treatment in the hospital," it added. Although the number of passengers on the ill-fated boat could not be immediately determined, the government said a rescue operation was under way. Boat accidents are common in Lagos as many communities and residents on islands in the city and other parts of the country travel to work, school and markets daily by boat, in some cases to avoid monster traffic jams. Seven people were killed in January last year when a boat carrying 17 passengers in the city capsized.