Police in Papua New Guinea fired gunshots Wednesday to quell a student protest demanding the prime minister's resignation, the government said. The country's police commissioner said nearly two dozen people were injured, but denied reports that as many as four people were killed, AP reported. Students in the South Pacific nation have been demanding for weeks that Prime Minister Peter O'Neill resign because of alleged corruption and mismanagement. Australian Foreign Minister Julie Bishop said she had been advised by the Australian embassy that police shot students in Port Moresby, the capital, as hundreds prepared to march from the University of Papua New Guinea to Parliament. Papua New Guinea Police Commissioner Gari Baki said no deaths had been reported. In a statement, Baki said 23 people believed to be university students were treated at hospitals after the clash. The head of the emergency ward at Port Moresby General Hospital told police that five of the students were in critical condition, Baki said. U.N. Secretary-General Ban Ki-moon called for calm and stressed "the importance of respect for peaceful protest and freedom of assembly, and a commitment to rule of law, dialogue and non-violence," spokesman Stephane Dujarric said.