COLOMBO, Oct. 28 (Xinhua) -- Three people were injured when firing took place inside the state-owned Petroleum Corporation in Dematagoda, in Sri Lanka's capital Colombo on Sunday, Police said.

Police Spokesperson, SP Ruwan Gunasekara, told Xinhua that a tense situation occurred when former Petroleum Minister Arjuna Ranatunga visited the Ceylon Petroleum Corporation office, with several Ceylon Petroleum Corporation workers resorting to a protest.

Gunasekara said the reason for the protest was still unclear but a security official from the minister's security team had opened fire, injuring 3 individuals.

The three injured were rushed to hospital while special security forces and additional police had been deployed inside the premises.

Police are conducting investigations, and the security official who opened fire has been arrested.

Sri Lanka is facing a political crisis after President Maithripala Sirisena sacked the Prime Minister Ranil Wickremesinghe on Friday, and appointed former President Mahinda Rajapakse as new PM.

A new caretaker government is expected to be sworn in on Monday.