A day after 63 people were killed and more than 150 injured in serial blasts that rocked Jaipur, it has come to light that the cycles that were used in the blasts were bought from the Pink City and the persons who bought the cycles have been identified.

"One of the shopkeepers identified a cycle as being bought from his shop and also gave a description of the person who bought the cycle. We have just released a sketch of the person," Rajasthan Director General of Police A S Gill said on Wednesday.

"We have called some people for questioning and getting information. We have not arrested anyone yet, though we have released the sketch of one of the perpetrators," Gill said.

Another senior police officer said that various police stations across Jaipur have picked up several people for questioning.

"We have picked up quite a few people for questioning and on the basis of suspicion. We can't give any figures of the number of people picked up since many police stations are working on this. But we have not made any arrests so far," Superintendent of Police (Jaipur East) V K Singh, under whose jurisdiction many of the blast sites fall, said on Wednesday.

But the police said the first person who was detained on Tuesday night might not be a suspect, the police said.

"There is not much there. It is nothing," Gill said.

Another officer explained that the man, reported to be hailing from Mumbai, might be a mentally unstable person and soon be released.

"That person is not able to speak coherently and he seems to be mentally unstable," a senior officer said.

On how a mentally unstable person came to be detained, he said: "Soon after the blasts, all the injured were rushed to the Sawai Man Singh Hospital. There the hospital authorities handed him over to the police, as they suspected something was wrong with him. So, he was taken to the police station for questioning," Singh said.

The police also said that the blasts could not have been carried out without the help of local hand, though it did not specify whether anyone from Jaipur is under suspicion.

"An operation of such level couldn't have been carried out without local help," an officer said. DGP Gill, however, said it is too soon to confirm whether anybody from the local population was involved.

The police, however, confirmed that RDX and ammonium nitrate were used in the blasts and the bombs were triggered using timer devices.

"While the defused bomb had plastic, traces of RDX and ammonium nitrate have been found in the other blast sites," Gill said.

Another officer confirmed that cheap alarm clocks were used as timer devices. "They had used those small alarm clocks that you get in the market for 25 rupees," he said.