Chapter 21 (pg 82-86) of the Sristi Khanda of Padma Purana recounts how Brahma killed a demon named Vajranabha and found Puskara.
Once Brahma wanted to perform a sacrifice. He went to earth to select a place for it. He arrived at a forest where the trees request him to stay and bless the place.
15.He meditated on the highest god who created this world. While meditating it came to his mind: 'How shall I perform a sacrifice?
16.Where on the earth—at which place—should I perform the sacrifice?
17.Kasi, Prayaga, Tuiiga and Naimisa and Sriikhala, so also Kafici, Bhadra, Devika, Kuruksetra and SarasvatI, Prabhasa and others are the
holy places on the earth.
21.When Brahma was thus thinking, this idea came to his mind: 'I now go to the earth.'
22-24. Reaching the place first, he entered that best forest, full of
many trees and creepers; adorned with many flowers; filled with the
notes of many birds; crowded with groups of many beasts; making gods
and demons fragrant with the perfumes of the abundant flowers of
trees; its ground was graced with flowers which were as it were
intentionally placed there.
All those rows of trees, seeing god Brahma who had arrived like that,
and presenting themselves to him with devotion, poured forth their
wealth of flowers. Accepting the flowers (offered) by the trees Brahma
said to them, "Welfare to you; ask for a boon."
The trees, free from (any) control, with humility (lit. with their
palms joined in obeisance) having saluted Brahma said: "If, O god,
affectionate towards people, who take refuge with you, you are
granting a boon then always stay by us in the forest."
Thus Brahma, the granter of boons, favoured the trees.
Brahma remains there for a 1000 years. He throws a lotus on the ground, its impact makes the earth and the heavens shake. The distressed and frightened gods enquire Vishnu of the cause. Vishnu takes them to Brahma.
63.Remaining (there) for a thousand years he threw a lotus on the ground. The earth by its fall trembled upto bottom.
64-65. Helpless oceans, with agitated waves, crossed their
boundary.Thousands of mountain-peaks occupied by tigers and vicious
elephants struck as it were with Indra's bolt, were shattered.
66-67. The mansions of gods and Siddhas (semi-divine beings
characterized by eight special faculties), the cities of Gandharvas
shook, tottered and penetrated the earth. The Kapota-clouds, showing a
collection of sheaths fell (i.e. showered rain) from the sky. There
were poignant suns, covering the clusters of luminaries.
68.Due to the great sound of that the three worlds with the mobile and immobile in it, rendered dumb, blind and deaf were frightened.
69-70. The bodies and minds of all gods and demons sank down and did
not know what it was. Mustering courage all of them looked for Brahma.
They did not know where Brahma had gone. (They could not understand)
why the earth quaked and why the omens and portents appeared.
71.Visnu just went there where the gods had remained. Gods saluting him said these words:
72-73. "O revered one, why is this appearance of omens and portents by
which, the three worlds as it were joined with death are made to
tremble, and the Kalpa has come to an end and the oceans have crossed
their boundaries? Why have the four steady quarter-elephants become
77.Thus addressed, Visnu, cherished by the supreme, said: "O gods, do not be alarmed; all of you listen to the cause of this.
78.This I, perceiving (the cause) definitely will tell you as it happened.
79.Revered Brahma, the grandsire of the worlds, with a lotus in his hand, settled in an extremely beautiful region—a heap of religious
merit—on the slope of mountains to perform a sacrifice.
80.And from his hand the lotus fell on the ground. It made a great sound which caused you to tremble.
81-84. There, being greeted with the fragrance of flowers by the
trees, he favoured the forest with beasts and birds, and for favouring
the world took delight in residing there. The revered one, benefactor
of the worlds, put up that best holy place (called) Puskara. Going
there with me propitiate Brahma. The revered one, when pleased, will
give you excellent boons."
Vishnu and the other gods pray to Brahma. Brahma appears to them and explains the cause of the sound.
Brahma, the best among those who know the Vedas, thus praised by gods (said to them): "All right, when remembered by you I shall give
(you what you want); your seeing me will be fruitful.
O sons, tell (me) what is desired by you; I shall give you excellent boons!" Thus addressed by the lord, the gods said (these)
124. "O revered one, this in itself is a great boon which is quite enough, that a good sound was heard by us when you threw the lotus.
125. Why did the earth tremble? Why were the people distressed? That cannot be without any purpose. Tell (us) the cause of this, O god."
126. This lotus is held by me for your good and for protecting the gods. Now listen what was the cause.
127. This demon Vajranabha by name, takes away the life of children. He remains taking shelter in the nether world.
128. Knowing about the arrival of you, remaining in penance, having laid down your weapons, the wicked one wanted to kill (you) the gods
along with Indra even.
129. I brought about his destruction by dropping the lotus; he was proud of his kingdom and splendour; so I killed him.
At this time there are in the world, devotees, brahmanas who have mastered the Vedas. May they not meet with misfortune, but may they
have good fortune.
O gods, I am equal (i.e. impartial) to gods, demons, men, reptiles, friends, and the entire host of beings.
132. I killed the sinner with a spell for your well-being. He has reached the worlds of the religious due to the sight of this lotus.
133. Since I dropped the lotus (here), therefore this place will be known as Puskara, a great, sanctifying holy place, giving religious merit.