Two days after a 23-year-old paramedical student was gang-raped and brutally assaulted in a moving bus, Delhi Police today claimed to have solved the case with the arrest of four people and said it will seek a fast-track trial for speedy punishment.The condition of the victim continued to be critical but "better than yesterday's", doctors said.br Delhi Police Commissioner Neeraj Kumar told a press conference that the driver of the chartered bus, which was not legally permitted to run on normal routes, his brother and two more people have been arrested, while a massive manhunt has been launched to nab the remaining two accused.