Nine in ten official results announced at polling units across the states in northwest and northeast place Muhammadu Buhari in clear lead ahead of incumbent President Goodluck Jonathan.
"In Bolori ward/sofon Maipanu Polling Unit 001, the APC polled 237 against PDP's 5; at Sofon Maipanu 2, APC got 237 while PDP garnered 13," Mahmoud Aliyu, an APC polling agent, told the Anadolu Agency in northeastern Maiduguri, the provincial capital of Borno State, displaying his copy of the result signed by agents of the other parties, including the ruling PDP.
AA reporter at the area confirmed the result which he said was read aloud before voters and agents at those polling centers.
The law empowers the polling official to count and announce results at the polling unit level.
Millions of Nigerians went to the polls Saturday to elect a new president, 360 House of Representatives members and 109 senators.
The presidential race is largely between Jonathan and Buhari, a former military ruler.
A total of 56,431,255 eligible voters were casting their ballot at 119, 973 polling centers across the country.
Election would hold on Sunday at some areas of the country, especially in southeast, where voter card reader failed to function probably.
Collation of results at ward and local government, meanwhile, continues through the night and to Sunday morning.
Final results for the presidential poll are not expected until Monday.
In Ali Fika, Bulabulin ward, APC polled 259 with the PDP claiming 3 votes while in Shehu Garbai old GRA polling unit, APC polled 504 while PDP got 60, according to result from the polling officer in Borno.
In Waziri Ibrahim Shehuri, APC boasted 157 while PDP polled 4, the results showed.
APC also won by wide margin in Lamisula/Jabamari and Maisandari, the largest ward in Maiduguri metropolis, among other places.
In Bauchi Club Polling Unit in northeastern Bauchi State, APC won with 352 as against PDP's 54.
"In Sakwari Tilden Filani polling unit, APC won with 486 votes," AA's Ogbodo Ndidi said, quoting official result from the polling unit level.
"In Jibril Aminu polling unit, the opposition polled 326 against 96 for the PDP," added our correspondent.
In northwest Kano, Jigawa, Kaduna, Zamfara and Kaduna, similar trend has been reported in favor of the opposition APC.
In Polling Unit 022 at Giginyu ward in Kano State's Nassarawa local government area, Buhari polled 324 as against 17 for Jonathan," according to official result sighted by AA's Muhammad Tijjani in the northwestern Kano, deemed to be Buhari's stronghold.
Similar trend is reported in the southwest which is the stronghold of the opposition party.
Official results from Lagos and Ogun states point at a huge win for Buhari, at least at the moment.
Results from much of north central, southeast and south south are not clear yet, partly because of crisis of the card reader in many areas there.
In north central Kwara State, many official results at polling units showed political shellacking in favor of Buhari.
Observers say the trend in the southwest and northwest, the country's two most populous regions, may point at danger for the president except an upset is recorded as more results come in.
The winner of the presidential race must clinch more than 50 percent of all valid votes plus a mandatory 25 percent in two-thirds of the country's 36 states.
If no candidate is able to win outright, the two frontrunners will compete for a simple majority in a runoff vote.
Aggrieved parties have 30 days from the election to legally challenge final poll results.