A man injured in bomb blasts is taken in a stretcher for treatment at the government medical college hospital in Patna, India, Sunday, Oct. 27, 2013. A series of small bomb blasts killed at least five people and injured dozens Sunday just hours before a massive campaign rally by the countryâs main opposition prime ministerial candidate Narendra Modi. AP Photo/Aftab Alam Siddiqui Two men injured in bomb blasts share a cot as they receive treatment at the government medical college hospital in Patna, India, Sunday, Oct. 27, 2013. A series of small bomb blasts killed several people Sunday just hours before a campaign rally by the country's main opposition prime ministerial candidate Narendra Modi. A series of small bomb blasts killed at least five people and injured dozens Sunday just hours before a massive campaign rally by the country's main opposition prime ministerial candidate Narendra Modi. India's main opposition Bharatiya Janata Party (BJP) 's prime ministerial candidate Narendra Modi sports a turban he was presented with at a rally in Patna, India, Sunday, Oct. 27, 2013. A series of small bomb blasts killed at least four people and injured dozens Sunday near a park in eastern India where tens of thousands of people had gathered to hear a speech by Modi. PATNA, India (AP) - A series of small bomb blasts killed five people and injured dozens Sunday in an east Indian city just before a massive campaign rally by the country's main opposition prime ministerial candidate in a nearby park. After the six homemade bombs went off in the Bihar state capital of Patna, panic and confusion erupted briefly among the hundreds of thousands of people gathered in the park to hear Narendra Modi of the Hindu nationalist Bharatiya Janata Party speak. Local reporters at the scene said authorities did not inform them of the blasts until the rally was over, and many people thought the explosions were from firecrackers or from cars misfiring. Authorities quickly restored order and the rally went ahead as scheduled. Modi made no mention of the blasts during his hourlong speech, but offered condolences later to the victims in a Twitter message. The longtime chief minister of western Gujarat state has been waging a fierce national campaign to unseat the Congress-led government in next year's elections. Police detained four men for questioning after the explosions, but did not say whether they were suspects. Prime Minister Manmohan Singh condemned the violence and appealed for peace and calm. The first blast came from a crude bomb that exploded in a public toilet building on an isolated railway platform, Patna district police chief Manu Maharaj said. Another bomb went off near a movie theater, and four more exploded just outside the park, sending plumes of gray smoke swirling above the crowd. "All the bombs produced low-intensity blasts," Maharaj said. An anti-sabotage team is investigating what happened. Five people died from the blasts and 73 were being treated for injuries, according to the head of Patna Medical College hospital, Vimal Karak. Bomb disposal and forensic teams found two unexploded bombs around the railway station and were defusing them, railway police superintendent Upendra Kumar Sinha said. Modi ignored the blasts during his speech and instead focused on criticizing Singh's government for India's high inflation. He also accused Bihar's highest elected leader, Nitish Kumar, of betraying the BJP after using its support to win his seat in the state. After the rally, Modi said the blasts were "deeply saddening" and offered condolences and prayers to the victims, according to a message posted from his official Twitter account. His plans to visit Bihar have been controversial since Kumar severed ties with the BJP six months ago to protest Modi's candidacy. Kumar has questioned Modi's secular credentials and suggested that he could exacerbate communal tensions between Hindus and Muslims in India. Over the past decade, Modi has been accused of ignoring a 2002 spate of violent attacks against Muslims in his home state of Gujarat - an allegation he has denied.