Motorcycle-borne unidentified men threw a hand grenade at a shop in the upscale Zamzama commercial area but there were no casualties.
This is the first time that such an attack has taken place in the area.
Investigations were underway into the incident and it appeared to be an extortion case, said newly-appointed Station House Officer of Clifton Ghazala Syed, who the first woman to be appointed as an SHO in Karachi.
Other similar hand grenade attacks took place in Gulistan-e-Jauhar - in which two persons were injured - and Safoora Goth, Korangi and Buffer zone.
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Police said four incidents were reported from Hyderabad and its outskirts.
Blasts were also reported on up-country railway tracks in Sehrish Nagar, Qasimabad taluka and Khursheed Colony of Kotri in Jamshoro district.
A blast occurred in the heart of Hyderabad outside Radio Pakistan building on Meeran Mohammad Shah road.
No one has claimed responsibility for these attacks yet.