A 26-year-old woman sub-inspector of the Delhi Police was shot dead near Rohini East Metro station on Friday night, a day before the Assembly elections in the national capital.
The SI, Preeti Ahlawat, was posted in Patparganj Industrial Area Police Station, police said.
A call about the incident was received around 9.30 pm, they said, adding she received gunshot wounds on her head.
"We have identified the suspects and CCTV footage of the area has been collected," said SD Mishra, Additional Commissioner of Police (Rohini).
Three empty cartridges were found from the spot, the officer said, adding a case has been registered and a probe is on.
Personal enmity is suspected to be the reason behind the killing, the officer said.
Ahlawat joined the Delhi Police in 2018.
The polling for the 70-member Delhi Assembly got underway on Saturday morning, an election that saw the ruling AAP, opposition BJP and the Congress engaged in a bitterly fought high-octane campaign.
Over 1.47 crore people are eligible to exercise their franchise in the polls that will decide the fate of 672 candidates.
Security forces kept a tight watch across the 70 constituencies, with police and paramilitary personnel keeping an "extra vigil" in sensitive areas like Shaheen Bagh, Jamia Nagar and Seelampuri.
There are over 81 lakh male voters, 66.80 lakh female voters, and 869 third-gender voters, Delhi Chief Electoral Officer (CEO) Ranbir Singh has said.
Around 2.33 lakh voters are in the age group of 18-19, 2.04 lakh voters are senior citizens aged 80, while there are 11,608 service voters, according to officials.
Prominent candidates in the fray include Chief Minister Arvind Kejriwal, his deputy Manish Sisodia, Atishi and Raghav Chadha of the AAP; four former mayors -- Azad Singh, Yogender Chandolia, Ravinder Gupta and Khushi Ram -- of the BJP; and Shivani Chopra, daughter of Delhi Congress president Subhash Chopra.
There are 13,750 polling booths, besides one auxiliary booth, located at 2,689 locations across Delhi.
"As far as critical polling stations are concerned, there are 516 locations and 3,704 booths in that category," Singh said.
Besides police security, polling stations falling in the "critical category" have got paramilitary cover. Activities at such stations are being monitored through webcasting, officials said.
All five polling stations in Shaheen Bagh, the epicentre of massive protests against the Citizenship (Amendment) Act, are under critical category.
Counting of votes will take place on Tuesday.
The Aam Aadmi Party is hoping to repeat its stellar performance of the last assembly polls when it won 67 of the 70 seats. The Bharatiya Janata Party, which bagged all the seven seats in Delhi in the 2019 Lok Sabha poll, is aiming to dislodge the AAP, while the Congress is seeking to better its performance than last time when it drew a blank in the assembly polls.
The AAP had got 54.3 per cent votes in the 2015 polls, while the BJP secured 32 per cent and the Congress bagged just 9.6 per cent.
