September 7, 2011 -- Updated 1103 GMT (1903 HKT)
- NEW: Home minister: Delhi is a terrorist target and is regularly placed on high alert
- This is the second blast outside the court complex in four months
- The bomb is placed in a briefcase outside a gate to the court
- Officials fear the death toll will rise
New Delhi, India (CNN) -- At least nine people were killed Wednesday after a bomb inside a briefcase exploded outside the Delhi High Court, India's home minister told lawmakers.
Delhi police said another 61 people were injured.
It was the second explosion outside the court complex in four months.
Wednesday's explosion took place on a particularly busy day at the court. The briefcase was placed in front of the Gate No. 5, used by litigants and lawyers.
Officials fear the death toll will rise.
"Whatever we could gather from the blast investigations is that it is an IED (improvised explosive device) with ammonium nitrate. We are working with the Delhi Police to get details," National Security Guard Director Gen. Rajen Medhekar told reporters.
No one immediately claimed responsibility for the attack.
The blast took place about 10:15 a.m., after the court opened and shortly before cases usually begin.
Wednesdays are dubbed "public interest litigation" days at the court, when many members of the public arrive to put cases before judges.
Pandemonium covered the streets of Delhi as emergency vehicles weaved around crowds, casualties were rushed off on stretchers and stunned residents wandered about with hands over their mouths.
The area was cordoned off, and police and bomb-sniffing dogs continued working the scene as rain poured.
The National Investigation Agency, a security agency set up after Mumbai terror attacks in 2008, was also investigating.
On May 25, ammonium nitrate wrapped in a bag and placed in a car outside the court's Gate No. 7 went off. No one was hurt in the explosion, but it prompted authorities to place the Delhi on high alert.
"Delhi is a target of terrorist groups. When parliament is in session, and during certain other times of the year, Delhi is placed on high alert," Home Minister P. Chidambaram told lawmakers.
Despite ongoing work between intelligence agencies and police, Chidambaram said, "at this stage, it is not possible to identify the group that caused the bomb blast today."
CNN's Andreena Narayan contributed to this report