A man who tried to force his way into Immigration Tower yesterday morning was the first person to be arrested after officials stepped up security following Wednesday's arson attack. The man refused to be searched but insisted on entering the building through the lobby to department offices. He was later released without charge. About 15 immigration officers and a team of police stood guard round-the-clock in the lobby yesterday. Public access to offices on the first and second floors was blocked and all members of the public had to go through the ground-floor lobby. Officers from the immigration investigation taskforce searched all people trying to visit the general investigation section. Wednesday's attack took place in the section's office on the 13th floor, which has been moved up one floor because of the damage. 'There are too many outsiders coming into the building which makes it very difficult for security checks,' a department officer said. 'We have to be more alert.' Several families of mainlanders filing applications for the right of abode at the department yesterday said they feared being made scapegoats for the actions of a few violent people. 'Why start a fire? It is very unnecessary and inappropriate,' said a woman accompanying her brother to apply for a visa extension on his mainland passport. 'If the right [of abode] is yours, it's yours. You shouldn't hurt others in order to get what you want.' A woman applying for residency for her two sons said the attack could undermine their chances of success. 'Everything can be negotiated. Starting a fire is a very selfish act. It affects everyone, not to mention innocent people,' she said.