Mayor Sovan Chatterjee (left) at the accident spot. (Sanjoy Chattopadhyaya)

Four persons were injured in Tollygunge on Friday after portions of a 21-year-old concrete footbridge over the Tolly’s Nullah collapsed.

Built in 1990, the 68-foot-long footbridge connects Kudghat with Karunamoyee and is used by thousands as a short cut between the two localities.

Around 7.15am, said police, the four men who were on the bridge had almost reached the Karunamoyee end when an iron beam holding up the concrete slabs came off the rusty foundation. The entire portion, along with the four men, was pulled down at least 12 feet below into the muck.

Passers-by rescued them and rushed them to MR Bangur Hospital. One of the injured, Alok Sarkar, was admitted. The others were released after being given first aid. A doctor said Sarkar had fractured his right ankle.

Witnesses said it was sheer luck that a major tragedy was avoided. Only 15 minutes earlier, a group of schoolchildren had used the bridge. Also, had the bridge given way in the middle, the pedestrians would have fallen into the canal waters, which could have caused fatalities.

“There are four schools in the area. Many children use the bridge around that time. Thankfully, no child was injured. The incident could have turned grave had the middle of the bridge collapsed,” said local Trinamul councillor Ratna Sur.

Residents alleged that the bridge was in poor shape. When mayor Sovan Chatterjee visited the spot, they demanded immediate repairs.

The mayor called up irrigation and waterways minister Manas Bhuniya and asked him to immediately make arrangements to repair the bridge.

According to Sur, the bridge had been concreted in 1990 after it had collapsed the year before, injuring several people.