"Remember Kenya will be there long after the elections".
Odinga has also rejected early results from Tuesday's vote indicating a strong lead for President Uhuru Kenyatta.
Police fired tear gas as several hundred protesters in the neighbourhood of Kondele - an epicentre of violence after disputed 2007 polls - set fire to barricades and tyres and placed rocks in the streets.
Odinga rejected the election's initial results, which showed him losing to the incumbent president, during the evening hours of August 8.
Nairobi police chief Japheth Koome says the two were shot as they took advantage of the protests to steal.
The controversy claimed by Odinga has led many to fear that a repeat of the violence after the 2007 election is a possibility, where more than 1,100 Kenyans died and 600,000 displaced. "Some people conspired and denied Kenyans an opportunity to elect their leaders", said Odinga.
One injured man was carried away by protesters who said police shot him.
"Vote and go home to wait for the results", the President said in response to a question about what his message to Kenyans was on election day.
While the 72-year-old presidential hopeful had appealed for calm, he said he could not control what his supporters choose to do.
The commission now has the hard task to convince anxious Kenyans that it has stuck to the promise of delivering free, fair and credible elections in the past.
The opposition candidate, a former political prisoner and self-described leftist, described the reported hack as an attack on Kenya's democracy and published 50 pages of computer logs on his Facebook page to support his claims.
His statements raised concerns of unrest over the results in Kenya, which has East Africa's biggest economy and is a regional hub.
In a communique, the observers said, to achieve this, IEBC personnel needed to be able to work freely in a secure environment, with time to complete the process.
Mr. Odinga alleged voting irregularities after losing to Mr. Kenyatta in the 2013 election and took his case to the Supreme Court, which ruled in Mr. Kenyatta's favour by saying the election was valid.
The allegations of fraud and corruption within the voting process has stirred protests, some violent, throughout the country as protesters and police clash.