Police say a mother and daughter played an active role in the attacks The involvement of an ordinary Muslim family in last week's deadly taxi explosions in Mumbai has introduced a worrying new element for security agencies tackling an increase in terrorist strikes across India. For the first time, women - a mother and daughter - have played an active role in bomb attacks. Under interrogation, the family told police that the motive behind the blasts, which killed 53 people, was revenge for the anti-Muslim riots in Gujarat state last year. The Indian government has so far downplayed any connection between the Gujarat riots, which sparked the killing of 2,000 Muslims, and the Mumbai bombing on August 25. Members of the Syed family - Syed Mohammed Hanif, 45, his wife Fahmida, 37, and daughter Farheen, 18 - were among four people arrested on Monday. The fourth, Arshad Shafiq Ansari, 25, an embroiderer who had fled the southern Gujarat city of Surat after the riots, was working as an autorickshaw driver in Mumbai. According to police, the Syed family left a bag containing explosives in a taxi parked alongside the historic Gateway of India monument, in front of the Taj Mahal Hotel. Ansari did likewise in the busy Zaveri Bazaar gem-and-jewellery market. When police found out about the involvement of the Syed family after arresting Ansari, they thought that the mother and daughter, as often in such cases, might have been unaware that the father had turned terrorist. But Maharashtra State Deputy Chief Minister Chhagan Bhujbal said police found that not only were the women involved in making the explosive devices, Fahmida also planted a bomb in a municipal bus in northeast Mumbai in July which killed two people and injured 25. 'That's what is so alarming about the situation,' a senior Mumbai crime branch officer told the Times of India. 'An entire family was involved.' The Syeds' neighbours in a shantytown in northeast Mumbai were shocked that the family had become serial bombers. 'They have lived here for nine years and never got into trouble,' one neighbour said. 'They were a conservative but simple family ... We just can't believe it.'