ISLAMABAD: Pakistani police defended Friday their response to a gunman who shut down the heart of the heavily guarded capital for five hours in a standoff that ended with him being shot and wounded.

Waving two semi-automatic guns and occasionally firing into the air, Mohammad Sikandar was accompanied by his wife and children throughout the tense drama late Thursday that took place close to Islamabad's political quarter.

Broadcast live on Pakistan's news channels, hours of stalemate came to a chaotic end when Zamurud Khan, a senior member of the opposition Pakistan Peoples Party sent to negotiate, made a sudden lunge at the gunman.

Khan slipped and missed his man, but police opened fire, seriously wounding Sikandar in the chest and leg before arresting him, dragging him off as blood poured from his wounds. Doctors said he was improving on Friday.

The drama in the centre of the normally sleepy capital drew a huge crowd of onlookers and media, and Islamabad police chief Muhammad Rizwan said they were to blame for the slow response, denying his men had dithered in the face of the challenge.

"The commando operation was delayed because we needed proper space between the general public and the gunman," he said on Geo News.

"We had asked media and the general public who had gathered there to stay at least 300 metres away for their own safety, but they did not move away."

Rizwan said there was a gap of only 50 metres (160 feet) between the crowd and Sikandar, making it impossible to tackle him safely.

He said it appeared Sikandar was not part of any extremist outfit.

"The preliminary investigations suggest that this man is not associated with any group and it was his own individual act," he told Geo News.