The security lapse comes two days ahead of the Bharatiya Janata Party national executive meeting which is being held in Goa where top leaders are expected to attend.
Cyrus D'Souza, a resident of Navelim, a village in south Goa, 40 km from Panaji, has been detained and sent to the Institute of Psychiatry and Human Behaviour here, for examination.
Both police and the chief minister's secretariat officials were unavailable for comment, but speaking to IANS Deputy Chief Minister Francis D'Souza confirmed the incident.
D'Souza said that Cyrus, dressed in military-like fatigues, slipped into the secretariat's elevator along with him and his staffers and started asking for the chief minister's office once inside.
"When he was told the chief minister is not in office he rushed towards the cabin irrespective and was accosted by guards, one of whom he assaulted," D'Souza said.
He further said that the assailant looked mentally disturbed and he had instructed the police to escort him to the institute.
"Who else would run to a CM's office?" asked D'Souza.
Bollywood celebs show you colours for Navratri 2017
Photos: Kareena Kapoor Khan, Kangana Ranaut at the Mumbai airport
Birthday special: Chris Gayle and his multiple records in cricket
In Pictures: 17 dreaded on-screen villains of Bollywood
'Ramayan' director's great granddaughter Sakshi's hottest photos