Seventy-six people died in Sunday’s terrorist attack in Uganda, but it could have been worse: An unexploded suicide vest was found at another site in Kampala, Uganda, a day after explosions tore into two city venues where people had gathered to watch the World Cup on TV. Four people, who weren’t Ugandan, were arrested in connection with the discovery. Police say the vest, uncovered at a suburban disco, contained ball bearings, just like those at the other blast sites. Islamist group al Shabaab claimed credit for the attacks, saying they are a response to the Ugandan government sending peacekeeping troops to Somalia, where the government there is struggling to hold on to control of just a small section of the capital as it fights Islamic militants. Officials worry Somalia is becoming a training ground for international terrorists; the explosions mark the first time al Shabaab has made good on threats to kill people outside Somalia.