There were also reports of voters boycotting the poll process in nine villages.
With the weather cooling down, voters queued up in good numbers at polling booths from 0700 hrs.
State Chief Electoral Officer Bhanwar Lal said 50 per cent voting was reported on an average in these constituencies till 1 PM.
Workers of YSR Congress, Telugu Desam and Congress reportedly clashed at a few polling booths while a woman voter, waiting to cast her vote in a polling booth at Ongole, died of cardiac arrest.
In Rayachoti constituency in Kadapa district, stones were pelted at the local TDP leader's house leading to some tension.
In Railway Kodur in Kadapa district, clashes were reported between YSRC and Congress workers.
War of words between YSR congress and Congress resulted in stone pelting, in which three persons sustained minor injuries and polling was stalled for two hours in the polling station. Police rushed to the polling booth and dispersed the mob.
Police also kept MLC B ChengalRayulu at Kodur under house arrest.
Also, YSR Congress leaders Janakiramaiah and Subba Reddy were arrested while they were allegedly distributing money to lure the voters on the polling day at Madhavaram village in Siddhavatam mandal, police said.
In the Polavaram ST Assembly segment, voters were reportedly boycotting the poll process in nine villages seeking a solution to their long-pending problems. In Nellore Lok Sabha constituency also, people are boycotting elections in two villages.
The elections are considered crucial as they are expected to have a bearing on the future of YSR chief Jaganmohan Reddy, who has been arrested in connection with a disproportionate assets case.