Police reach the site an hour later to disperse the crowd and cordon off the area.
Doctors say the child is out of danger; Rescue 1122 team will hand child over to Edhi team.
Convict, who hailed from Muzafargarh, had been found guilty of killing a man in 1994.
SP (City) Khalid Rauf says children wounded after they retrieved a grenade from Naubahar canal and pulled out its pin.
Two executions in Karachi, 3 in Jhang, 2 in Rawalpindi, 2 in Mianwali and one each in Multan, Gujranwala and Faisalabad.
Speaking to the media, Hashmi conceded his defeat and congratulated the PTI-backed candidate for winning the by-election
PTI leader Shah Mehmood Qureshi, through a statement, announced his party will not be contesting by-polls for the seat.
More measures underway to secure the remaining part of Multan.
The section, which has been imposed in the city for two days, appears to be aimed at restricting political gatherings.