Tension is rising in the run-up to the final battle over the electoral reform package. In a disturbing development, 10 people were arrested yesterday after police found materials that could be used for making explosives. Based on the evidence gathered by the police, the suspects appear to have been plotting some kind of dastardly act ahead of the Legislative Council vote on the reform package this week. If true, this would be a serious threat to public safety, with lives potentially at risk. The suspects are aged 21 to 58, some of whom are said to belong to a "local radical group" called the National Independent Party. Police would not say how many of those from the group had been arrested. But a police source said the group had discussed launching a bomb attack earlier on the internet. Investigations are still ongoing and the possibility of more arrests cannot be ruled out. The arrests have aroused heated discussion on social media. While some have expressed worries over the growing tension, others questioned whether there was evidence to link the alleged making of explosives with the Legco vote. Following the 79-day pro-democracy Occupy movement last year, there has been growing concern of similar protests when lawmakers vote on the reform package. Although those involved in Occupy have repeatedly said there is no plan of another blockade, the tension is palpable. In what is seen as a sign of a tougher approach towards protesters, police officers removed heaps of objects deemed dangerous from people camping outside the Legco complex at the weekend. The Legco Commission has also mapped out detailed measures to reduce the security risk for lawmakers and officials attending the meeting. It is imperative that the vote be conducted in a civilised manner without threat of violence. Sunday's march against the government's reform package attracted a lower-than-expected turnout and did not result in any chaos or violence. But emotions are still running high. Activists plan to rally outside Legco in the evenings, with the momentum expected to peak when the vote is taken. The electoral reform plan is undoubtedly controversial. But that is not an excuse to act outside the law. Those who have breached the law should be punished accordingly. Protesters should exercise self-restraint and avoid confrontation or violence.