New Delhi: Twenty-two people were killed and at least 130 injured as serial blasts ripped through crowded shopping areas across Delhi on Saturday.
Indian Mujahideen, the Islamic outfit that was allegedly behind Ahmedabad blasts, also claimed responsibility for the blasts.
Police and witnesses said two bombs went off in dustbins in and around Connaught Place, a shopping and dining area popular with tourists and locals in the city centre.
Others exploded within minutes of each other in busy markets around the city.
Security in Mumbai, Hyderabad, Pune, and other metros has been heightened and police claim a probe has begun in full earnest.
The Mumbai police cyber crime cell is investigating the terror e-mail sent by the Indian Mujahideen to various media organisations minutes before the blast. [Also Read: Indian Mujahideen claims Operation B-A-D over]
The mail was reportedly sent through a cracked wi-fi account from the Chembur suburb of Mumbai.
The mail sent from email@example.com, virtually challenged the security agencies to "do whatever you want and stop us if you can”. [Read Story: How Indian Mujahideen strikes at will]
Meanwhile, the police in Delhi, Gujarat and Rajasthan are looking at links between the Delhi blasts and the terror attacks in Jaipur and Ahmedabad.
The Indian Mujahideen is understood to be staffed by activists of the banned Students Islamic Movement of India (SIMI) and intelligence agencies are also probing that angle.
Forensic teams in Delhi are trying to determine the contents of the bombs.
Sources say the bombs used ammonium nitrate with fuel oil, and were packed with metal ball bearings for maximum impact.
The Maharastra ATS is now looking at gathering more detail about the email.
"The email was sent from Mumbai.Internet router system is trying to trace it.The cyber cell is also investigating," Maharashtra ATS chief, Hemant Karkare, said.